Non-heat cleaned fabrics and products including the same

ABSTRACT

The present invention provides non-heat cleaned glass fiber fabrics comprising resin compatible coatings that offer higher tensile strengths than corresponding fabrics that have been heat cleaned and silane finished. These fabrics can be used in a wide variety of applications, such as reinforcements for composites such as printed circuit boards. 
     In one nonlimiting embodiment, the invention provides a non-heat cleaned fabric comprising a plurality of fiber strands in a warp direction and a fill direction, each fiber strand comprising a plurality of E-glass fiber, and having a resin compatible coating composition on at least a portion of a surface of at least one fiber strand, wherein the fabric has a tensile strength of at least 267 Newtons when measured in the warp direction or fill direction. Although not required, the fabric also has a tensile strength of at least 1.5 times that of a corresponding fabric that is heat cleaned by heating the corresponding fabric to a temperature of at least 380° C. for at least 60 hours and silane finished when measured in the warp direction or fill direction.

RELATED APPLICATIONS

This application is a continuing application of U.S. patent applicationSer. No. 09/527,034 of Novich et al. entitled “Impregnated Glass FiberStrands and Products Including the Same”, filed Mar. 16, 2000, whichclaims the benefit of U.S. Provisional Application Nos. 60/146,605 filedJul. 30, 1999; No. 60/146,862 filed Aug. 3, 1999; and No. 60/183,562filed Feb. 18, 2000.

This application also claims the benefit of U.S. Provisional ApplicationNo. 60/233,460 filed Sep. 18, 2000.

This invention relates generally to non-heat cleaned fabric comprisingresin compatible yarn and, in particular to the tensile strength of suchfabrics.

In thermosetting molding operations, good “wet-through” (penetration ofa polymeric matrix material through the mat or fabric) and “wet-out”(penetration of a polymeric matrix material through the individualbundles or strands of fibers in the mat or fabric) properties aredesirable. In contrast, good dispersion properties (i.e., gooddistribution properties of fibers within a thermoplastic material) areof predominant concern in typical thermoplastic molding operations.

In the case of composites or laminates formed from fiber strands woveninto fabrics, in addition to providing good wet-through and good wet-outproperties of the strands, it is desirable that the coating on thesurfaces of the fibers strands protect the fibers from abrasion duringprocessing, provide for good weavability, particularly on air-jet loomsand be compatible with the polymeric matrix material into which thefiber strands are incorporated. However, many sizing components are notcompatible with the polymeric matrix materials and can adversely affectadhesion between the glass fibers and the polymeric matrix material. Forexample, starch, which is a commonly used sizing component for textilefibers, is generally not compatible with polymeric matrix material. As aresult, these incompatible materials must be removed from the fabricprior to impregnation with the polymeric matrix material.

The removal of such non-resin compatible sizing materials, i.e.,de-greasing or de-oiling the fabric, can be accomplished through avariety of techniques. The removal of these non-resin compatible sizingmaterials is most commonly accomplished by exposing the woven fabric toelevated temperatures for extended periods of time to thermallydecompose the sizing(s) (commonly referred to as heat-cleaning). Aconventional heat-cleaning process involves heating the fabric at 380°C. for 60-80 hours. However, such heat cleaning steps are detrimental tothe strength of the glass fibers, are not always completely successfulin removing the incompatible materials and can further contaminate thefabric with sizing decomposition products. Other methods of removingsizing materials have been tried, such as water washing and/or chemicalremoval. However, such methods generally require significantreformulation of the sizing compositions for compatibility with suchwater washing and/or chemical removal operations and are generally notas effective as heat-cleaning in removing all the incompatible sizingmaterials.

In addition, since the weaving process can be quite abrasive to thefiber glass yarns, those yarns used as warp yarns are typicallysubjected to a secondary coating step prior to weaving, commonlyreferred to as “slashing”, to coat the warp yarns with an abrasionresistance coating (commonly referred to as a “slashing size”) to helpminimize abrasive wear of the glass fibers. The slashing size isgenerally applied over the primary size that was previously applied tothe glass fibers during the fiber forming operation. However, sincetypical slashing sizes are also not generally compatible with thepolymeric matrix materials, they too must be removed from the wovenfabric prior to its incorporation into the resin. A commonly usedslashing size is polyvinyl alcohol (PVA).

Furthermore, to improve adhesion between the de-greased or de-oiledfabric and the polymeric resin, a finishing size, typically a silanecoupling agent and water, is applied to the fabric to re-coat the glassfibers in yet another processing step (commonly called “finishing”).

All of these non-value added processing steps-slashing, de-greasing orde-oiling, and finishing-increase fabric production cycle time and cost.Additionally, they generally require significant investment in capitalequipment and labor. Moreover, the added handling of the fabricassociated with these processing steps can lead to fabric damage anddecreased quality.

Efforts have been directed toward improving the efficiency oreffectiveness of some of these processing steps. There neverthelessremains a need for coatings that can accomplish one or more of thefollowing: inhibit abrasion of glass fibers; inhibit breakage of glassfibers; be compatible with a wide variety of matrix materials; andprovide for good wet-out by the matrix material and wet-through by thematrix material. In addition, it would be particularly advantageous ifthe coatings were compatible with modern air-jet weaving equipment toincrease productivity. Furthermore, it would be advantageous toeliminate the non-value added processing steps in a fabric formingoperation while maintaining the fabric quality required for electronicsupport applications and providing for good laminate properties.

The present invention provides non-heat cleaned glass fiber fabricscomprising resin compatible coatings that offer higher tensile strengthsthan corresponding fabrics that have been heat cleaned and silanefinished. These fabrics can be used in a wide variety of applications,such as reinforcements for composites such as printed circuit boards.

The foregoing summary, as well as the following detailed description ofembodiments of the present invention, will be better understood whenread in conjunction with the appended drawings. In the drawings:

FIG. 1 is a perspective view of a coated fiber strand at least partiallycoated with a coating composition according to the present invention;

FIG. 2 is a perspective view of a coated fiber strand at least partiallycoated with a sizing composition and a secondary coating compositionaccording to the present invention on at least a portion of the sizingcomposition;

FIG. 3 is a perspective view of a coated fiber strand at least partiallycoated with a sizing composition, a secondary coating composition on atleast a portion of the sizing composition, and a tertiary coatingcomposition according to the present invention on at least a portion ofthe secondary coating composition;

FIG. 4 is a top plan view of a composite product according to thepresent invention;

FIG. 5 is a top plan view of a fabric according to the presentinvention;

FIG. 6 is a schematic diagram of a method for assembling a fabric andforming a laminate according to the present invention;

FIG. 7 is a cross-sectional view of an electronic support according tothe present invention;

FIGS. 8 and 9 are cross-sectional views of alternate embodiments of anelectronic support according to the present invention;

FIG. 10 is a schematic diagram of a method for forming an aperture in alayer of fabric of an electronic support;

The fiber strands of the present invention have a unique coating thatnot only can inhibit abrasion and breakage of the fibers duringprocessing but also provides at least one of the following properties:good wet-through, wet-out and dispersion properties in formation ofcomposites. As fully defined below, a “strand” comprises a plurality ofindividual fibers, i.e., at least two fibers. As used herein,“composite” means the combination of the coated fiber strand of thepresent invention with an additional material, for example, but notlimited to, one or more layers of a fabric incorporating the coatedfiber strand combined with a polymeric matrix material to form alaminate. Good laminate strength, good thermal stability, goodhydrolytic stability (i.e. resistance to migration of water along thefiber/polymeric matrix material interface), low corrosion and reactivityin the presence of high humidity, reactive acids and alkalies andcompatibility with a variety of polymeric matrix materials, which caneliminate the need for removing the coating, and in particular heat orpressurized water cleaning, prior to lamination, are other desirablecharacteristics which can be exhibited by the coated fiber strands ofthe present invention.

The coated fiber strands of the present invention can provide goodprocessability in weaving and knitting. Low fuzz and halos, low brokenfilaments, low strand tension, high fliability and low insertion timeare examples of some desirable characteristics, individually or incombination, that can be provided by the coated glass fiber strands ofthe present invention. As a result, the coated fiber strands of thepresent invention can facilitate weaving and knitting, and canconsistently provide a fabric with few surface defects for printedcircuit board applications. In addition, coated fiber strands of thepresent invention can be suitable for use in an air jet weaving process.As used herein, “air jet weaving” means a type of fabric weaving inwhich the fill yarn (weft) is inserted into the warp shed by a blast ofcompressed air from one or more air jet nozzles.

The coated fiber strands of the present invention can have a uniquecoating that can facilitate thermal conduction along coated surfaces ofthe fibers. When used as a continuous reinforcement for an electroniccircuit board, such coated glass fibers of the present invention canprovide a mechanism to promote heat dissipation from a heat source (suchas a chip or circuit) along the reinforcement to conduct heat away fromthe electronic components and thereby inhibit thermal degradation and/ordeterioration of the circuit components, glass fibers and polymericmatrix material. The coated glass fibers of the present invention canprovide a higher thermal conductivity phase than the matrix material,i.e., a path for heat dissipation and distribution, thereby reducingdifferential thermal expansion and warpage of the electronic circuitboard and improving solder joint reliability.

The coated glass fiber strands of the present invention can lessen oreliminate the need for incorporating thermally conductive materials inthe matrix resin, which improves laminate manufacturing operations andlowers costly matrix material supply tank purging and maintenance.

The coated fiber strands of the present invention can possess highstrand openness. As used herein, the term “high strand openness” meansthat the strand has an enlarged cross-sectional area and that thefilaments of the strand are not tightly bound to one another. The highstrand openness can facilitate penetration or wet out of matrixmaterials into the strand bundles.

Composites, and in particular laminates, of the present invention, madefrom the fiber strands of the present invention, can possess at leastone of the following properties: low coefficient of thermal expansion;good flexural strength; good interlaminar bond strength; and goodhydrolytic stability, i.e., the resistance to migration of water alongthe fiber/matrix interface. Additionally, electronic supports andprinted circuit boards of the present invention made from the fiberstrands in accordance with the present invention can have at least oneof the following properties: good drillability; and resistance to metalmigration (also referred to as cathodic-anodic filament formation orCAF). See Tummala (Ed.) et al., Microelectronics Packaging Handbook,(1989) at pages 896-897 and IPC-TR-476B, “Electrochemical Migration:Electrochemically Induced Failures in Printed Wiring Boards andAssemblies”, (1997) which are specifically incorporated by referenceherein. Fiber strands in accordance with the present invention with gooddrillability have at least one of low tool wear during drilling and goodlocational accuracy of drilled holes.

As described above, typical fabric forming operations involve subjectingfiber glass yarns and fabric made therefrom to several non-value addedprocessing steps, such as slashing, heat-cleaning and finishing. Thepresent invention provides methods of forming fabrics, laminates,electronic supports and printed circuit boards that eliminate non-valueadded processing steps from the fabric forming process while providingfabrics having quality suitable for use in electronic packagingapplications. Other advantages of embodiments of the present inventioninclude, but are not limited to, reduced production cycle time,elimination of capital equipment, reduced fabric handling and laborcosts, good fabric quality and good final product properties.

The present invention also provides methods to inhibit abrasive wear offiber strands from contact with other solid objects, such as portions ofa winding, weaving or knitting device, or by interfilament abrasion byselecting fiber strands having a unique coating of the presentinvention.

For the purposes of this specification, unless otherwise indicated, allnumbers expressing quantities of ingredients, reaction conditions, andso forth used in the specification and claims are to be understood asbeing modified in all instances by the term “about.” Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Referring now to FIG. 1, wherein like numerals indicate like elementsthroughout, there is shown in FIG. 1 a coated fiber strand 10 comprisinga plurality of fibers 12, according to the present invention. As usedherein, “strand” means a plurality of individual fibers, i.e., at leasttwo fibers, and the strand can comprise fibers made of differentfiberizable materials. (The bundle of fibers can also be referred to as“yarn”.) The term “fiber” means an individual filament. Although notlimiting the present invention, the fibers 12 can have an averagenominal fiber diameter ranging from 3 to 35 micrometers. In oneembodiment, the average nominal fiber diameter of the present inventioncan be 5 micrometers and greater. For “fine yarn” applications, theaverage nominal fiber diameter can range from 5 to 7 micrometers.

The fibers 12 can be formed from any type of fiberizable material knownto those skilled in the art including fiberizable inorganic materials,fiberizable organic materials and mixtures of any of the foregoing. Theinorganic and organic materials can be either man-made or naturallyoccurring materials. One skilled in the art will appreciate that thefiberizable inorganic and organic materials can also be polymericmaterials. As used herein, the term “polymeric material” means amaterial formed from macromolecules composed of long chains of atomsthat are linked together and that can become entangled in solution or inthe solid state¹. As used herein, the term “fiberizable” means amaterial capable of being formed into a generally continuous filament,fiber, strand or yarn.

¹ James Mark et al. Inorganic Polymers, Prentice Hall Polymer Scienceand Engineering Series, (1992) at page 1 which is hereby incorporated byreference.

The fibers 12 can be formed from an inorganic, fiberizable glassmaterial. Fiberizable glass materials useful in the present inventioninclude, but are not limited to, those prepared from fiberizable glasscompositions such as “E-glass”, “A-glass”, “C-glass”, “D-glass”,“R-glass”, “S-glass”, and E-glass derivatives. As used herein, “E-glassderivatives” means glass compositions that comprise minor amounts offluorine and/or boron and can be fluorine-free and/or boron-free.Furthermore, as used herein, “minor amounts of fluorine” means less than0.5 weight percent fluorine, such as, for example, less than 0.1 weightpercent fluorine, and “minor amounts of boron” means less than 5 weightpercent boron, such as, for example, less than 2 weight percent boron.Basalt and mineral wool are examples of other fiberizable glassmaterials useful in the present invention. In one embodiment, the glassfibers can be formed from E-glass or E-glass derivatives. Suchcompositions are well known to those skilled in the art and furtherdiscussion thereof is not believed to be necessary in view of thepresent disclosure.

The glass fibers of the present invention can be formed in any suitablemethod known in the art, for forming glass fibers. For example, glassfibers can be formed in a direct-melt fiber forming operation or in anindirect, or marble-melt, fiber forming operation. In a direct-meltfiber forming operation, raw materials are combined, melted andhomogenized in a glass melting furnace. The molten glass moves from thefurnace to a forehearth and into fiber forming apparatuses where themolten glass is attenuated into continuous glass fibers. In amarble-melt glass forming operation, pieces or marbles of glass havingthe final desired glass composition are preformed and fed into a bushingwhere they are melted and attenuated into continuous glass fibers. If apremelter is used, the marbles are fed first into the premelter, melted,and then the melted glass is fed into a fiber forming apparatus wherethe glass is attenuated to form continuous fibers. In the presentinvention, the glass fibers can be formed by the direct-melt fiberforming operation. For additional information relating to glasscompositions and methods of forming the glass fibers, see K.Loewenstein, The Manufacturing Technology of Continuous Glass Fibres,(3d Ed. 1993) at pages 30-44, 47-103, and 115-165; U.S. Pat. Nos.4,542,106 and 5,789,329; and IPC-EG-140 “Specification for FinishedFabric Woven from ‘E’ Glass for Printed Boards” at page 1, a publicationof The Institute for Interconnecting and Packaging Electronic Circuits(June 1997), which are specifically incorporated by reference herein.

Nonlimiting examples of suitable non-glass fiberizable inorganicmaterials include ceramic materials such as silicon carbide, carbon,graphite, mullite, aluminum oxide and piezoelectric ceramic materials.Nonlimiting examples of suitable fiberizable organic materials includecotton, cellulose, natural rubber, flax, ramie, hemp, sisal and wool.Nonlimiting examples of suitable fiberizable organic polymeric materialsinclude those formed from polyamides (such as nylon and aramids),thermoplastic polyesters (such as polyethylene terephthalate andpolybutylene terephthalate), acrylics (such as polyacrylonitriles),polyolefins, polyurethanes and vinyl polymers (such as polyvinylalcohol). Non-glass fiberizable materials useful in the presentinvention and methods for preparing and processing such fibers arediscussed at length in the Encyclopedia of Polymer Science andTechnology, Vol. 6 (1967) at pages 505-712, which is specificallyincorporated by reference herein.

It is understood that blends or copolymers of any of the above materialsand combinations of fibers formed from any of the above materials can beused in the present invention, if desired. Moreover, the term strandencompasses at least two different fibers made from differingfiberizable materials. In one embodiment, the fiber strands of thepresent invention contain at least one glass fiber, although they maycontain other types of fibers.

The present invention will now be discussed generally in the context ofglass fiber strands, although one skilled in the art would understandthat the strand 10 can comprise fibers 12 formed from any fiberizablematerial known in the art as discussed above. Thus, the discussion thatfollows in terms of glass fibers applies generally to the other fibersdiscussed above.

With continued reference to FIG. 1, in another embodiment, at least oneand possibly all of the fibers 12 of fiber strand 10 of the presentinvention have a layer 14 of a coating composition, which can be aresidue of a coating composition, on at least a portion 17 of thesurfaces 16 of the fibers 12 to protect the fiber surfaces 16 fromabrasion during processing and inhibit fiber breakage. The layer 14 canbe present on the entire outer surface 16 or periphery of the fibers 12.

The coating compositions of the present invention can be aqueous coatingcompositions such as aqueous, resin compatible coating compositions.Although not preferred for safety reasons, the coating compositions cancontain volatile organic solvents such as alcohol or acetone as needed,but generally are free of such solvents. Additionally, the coatingcompositions of the present invention can be used as primary sizingcompositions and/or secondary sizing or coating compositions.

As used herein, in one embodiment the terms “size”, “sized” or “sizing”refers to any coating composition applied to the fibers. The terms“primary size” or “primary sizing” refer to a coating compositionapplied to the fibers immediately after formation of the fibers. Theterms “secondary size”, “secondary sizing” or “secondary coating” meancoating compositions applied to the fibers after the application of aprimary size. The terms “tertiary size”, “tertiary sizing” or “tertiarycoating” mean coating compositions applied to the fibers after theapplication of a secondary size. These coatings can be applied to thefiber before the fiber is incorporated into a fabric or it can beapplied to the fiber after the fiber is incorporated into a fabric, e.g.by coating the fabric. In an alternative embodiment, the terms “size”,“sized” and “sizing” additionally refer to a coating composition (alsoknown as a “finishing size”) applied to the fibers after at least aportion, and possibly all of a conventional, non-resin compatible sizingcomposition has been removed by heat or chemical treatment, i.e., thefinishing size is applied to bare glass fibers incorporated into afabric form.

As used herein, the term “resin compatible” means the coatingcomposition applied to the glass fibers is compatible with the matrixmaterial into which the glass fibers will be incorporated such that thecoating composition (or selected coating components) achieves at leastone of the following properties: does not require removal prior toincorporation into the matrix material (such as by de-greasing orde-oiling), facilitates good wet-out and wet-through of the matrixmaterial during conventional processing and results in final compositeproducts having desired physical properties and hydrolytic stability.

The coating composition of the present invention comprises one or moreparticles, such as a plurality of particles 18, that when applied to atleast one fiber 23 of the plurality of fibers 12 adhere to the outersurface 16 of the at least one fiber 23 and provide one or moreinterstitial spaces 21 between adjacent glass fibers 23, 25 of thestrand 10 as shown in FIG. 1. These interstitial spaces 21 correspondgenerally to the size 19 of the particles 18 positioned between theadjacent fibers. The particles 18 of the present invention can bediscrete particles. As used herein, the term “discrete” means that theparticles do not tend to coalesce or combine to form continuous filmsunder conventional processing conditions, but instead substantiallyretain their individual distinctness, and generally retain theirindividual shape or form. The discrete particles of the presentinvention may undergo shearing, i.e., the removal of a layer or sheet ofatoms in a particle, necking, i.e., a second order phase transitionbetween at least two particles, and partial coalescence duringconventional fiber processing, and still be considered to be “discrete”particles.

The particles 18 of the present invention can be dimensionally stable.As used herein, the term “dimensionally stable particles” means that theparticles will generally maintain their average particle size and shapeunder conventional fiber processing conditions, such as the forcesgenerated between adjacent fibers during weaving, roving and otherprocessing operations, so as to maintain the desired interstitial spaces21 between adjacent fibers 23, 25. In other words, dimensionally stableparticles generally will not crumble, dissolve or substantially deformin the coating composition to form a particle having a maximum dimensionless than its selected average particle size under typical glass fiberprocessing conditions, such as exposure to temperatures of up to 25° C.,for example up to 100° C., and up to 140° C. Additionally, the particles18 should not substantially enlarge or expand in size under glass fiberprocessing conditions and, more particularly, under composite processingconditions where the processing temperatures can exceed 150° C. As usedherein, the phrase “should not substantially enlarge in size” inreference to the particles means that the particles should not expand orincrease in size to more than approximately three times their initialsize during processing. Furthermore, as used herein, the term“dimensionally stable particles” covers both crystalline andnon-crystalline particles.

In one embodiment, the coating compositions of the present invention canbe substantially free of heat expandable particles. As used herein, theterm “heat expandable particles” means particles filled with orcontaining a material, which, when exposed to temperatures sufficient tovolatilize the material, expand or substantially enlarge in size. Theseheat expandable particles therefore expand due to a phase change of thematerial in the particles, e.g., a blowing agent, under normalprocessing conditions. Consequently, the term “non-heat expandableparticle” refers to a particle that does not expand due a phase changeof the material in the particle under normal fiber processingconditions, and, in one embodiment of the present invention, the coatingcompositions comprise at least one non-heat expandable particle.

Generally, the heat expandable particles can be hollow particles with acentral cavity. In an embodiment of the present invention, the cavitycan be at least partial filled with a non-solid material such as a gas,liquid, and/or a gel.

As used herein, the term “substantially free of heat expandableparticles” means less than 50 weight percent of heat expandableparticles on a total solids basis, such as less than 35 weight percent.In another embodiment, the coating compositions of the present inventioncan be essentially free of heat expandable particles. As used herein,the term “essentially free of heat expandable particles” means thesizing composition comprises less than 20 weight percent of heatexpandable particles on a total solids basis, such as, for example, lessthan 5 weight percent, and less than 0.001 weight percent.

The particles 18 can be non-waxy. The term “non-waxy” means thematerials from which the particles are formed are not wax-like. As usedherein, the term “wax-like” means materials composed primarily ofunentangled hydrocarbons chains having an average carbon chain lengthranging from 25 to 100 carbon atoms^(2,3).

² L. H. Sperling Introduction of Physical Polymer Science, John Wileyand Sons, Inc. (1986) at pages 2-5, which are specifically incorporatedby reference herein. ³ W. Pushaw, et al. “Use of Micronised Waxes andWax Dispersions in Waterborne Systems” Polymers, Paint, Colours Journal,V.189, No. 4412 January 1999 at pages 18-21 which are specificallyincorporated by reference herein.

In one embodiment of the present invention, the particles 18 in thepresent invention can be discrete, dimensionally stable, non-waxyparticles.

The particles 18 can have any shape or configuration desired. Althoughnot limiting in the present invention, examples of suitable particleshapes include, but are not limited to, spherical (such as beads,microbeads or hollow spheres), cubic, platy or acicular (elongated orfibrous). Additionally, the particles 18 can have an internal structurethat is hollow, porous or void free, or a combination thereof, e.g. ahollow center with porous or solid walls. For more information onsuitable particle characteristics see H. Katz et al. (Ed.), Handbook ofFillers and Plastics (1987) at pages 9-10, which are specificallyincorporated by reference herein.

The particles 18 can be formed from materials selected from polymericand non-polymeric inorganic materials, polymeric and non-polymericorganic materials, composite materials, and mixtures of any of theforegoing. As used herein, the term “polymeric inorganic material” meansa polymeric material having a backbone repeat unit based on an elementor elements other than carbon. For more information see J. E. Mark etal. at page 5, which is specifically incorporated by reference herein.As used herein, the term “polymeric organic materials” means syntheticpolymeric materials, semisynthetic polymeric materials and naturalpolymeric materials having a backbone repeat unit based on carbon.

An “organic material”, as used herein, means carbon containing compoundswherein the carbon is typically bonded to itself and to hydrogen, andoften to other elements as well, and excludes binary compounds such asthe carbon oxides, the carbides, carbon disulfide, etc.; such ternarycompounds as the metallic cyanides, metallic carbonyls, phosgene,carbonyl sulfide, etc.; and carbon-containing ionic compounds such asthe metallic carbonates, such as calcium carbonate and sodium carbonate.See R. Lewis, Sr., Hawley's Condensed Chemical Dictionary, (12th Ed.1993) at pages 761-762, and M. Silberberg, Chemistry The MolecularNature of Matter and Change (1996) at page 586, which are specificallyincorporated by reference herein.

As used herein, the term “inorganic materials” means any material thatis not an organic material.

As used herein, the term “composite material” means a combination of twoor more differing materials. The particles formed from compositematerials generally have a hardness at their surface that is differentfrom the hardness of the internal portions of the particle beneath itssurface. More specifically, the surface of the particle can be modifiedin any manner well known in the art, including, but not limited to,chemically or physically changing its surface characteristics usingtechniques known in the art, such that the surface hardness of theparticle can be equal to or less than the hardness of the glass fiberswhile the hardness of the particle beneath the surface can be greaterthan the hardness of the glass fibers. For example, a particle can beformed from a primary material that is coated, clad or encapsulated withone or more secondary materials to form a composite particle that has asofter surface. In yet another alternative embodiment, particles formedfrom composite materials can be formed from a primary material that iscoated, clad or encapsulated with a different form of the primarymaterial. For more information on particles useful in the presentinvention, see G. Wypych, Handbook of Fillers, 2nd Ed. (1999) at pages15-202, which are specifically incorporated by reference herein.

Representative non-polymeric, inorganic materials useful in forming theparticles 18 of the present invention include, but are not limited to,inorganic materials selected from graphite, metals, oxides, carbides,nitrides, borides, sulfides, silicates, carbonates, sulfates andhydroxides. A nonlimiting example of a suitable inorganic nitride fromwhich the particles 18 can be formed is boron nitride, an embodiment ofthe present invention, such as boron nitride particles having ahexagonal crystal structure. A nonlimiting example of a useful inorganicoxide is zinc oxide. Suitable inorganic sulfides include, but are notlimited to, molybdenum disulfide, tantalum disulfide, tungsten disulfideand zinc sulfide. Useful inorganic silicates include, but are notlimited to, aluminum silicates and magnesium silicates, such asvermiculite. Suitable metals include, but are not limited to,molybdenum, platinum, palladium, nickel, aluminum, copper, gold, iron,silver, alloys, and mixtures of any of the foregoing.

In one embodiment of the invention, the particles 18 can be formed fromsolid lubricant materials. As used herein, the term “solid lubricant”means any solid used between two surfaces to provide protection fromdamage during relative movement and/or to reduce friction and wear. Inone embodiment, the solid lubricants can be inorganic solid lubricants.As used herein, “inorganic solid lubricant” means that the solidlubricants have a characteristic crystalline habit which causes them toshear into thin, flat plates which readily slide over one another andthus produce an antifriction lubricating effect between the fibersurfaces, such as the glass fiber surface, and an adjacent solidsurface, at least one of which is in motion. See R. Lewis, Sr., Hawley'sCondensed Chemical Dictionary, (12th Ed. 1993) at page 712, which isspecifically incorporated by reference herein. Friction is theresistance to sliding one solid over another. F. Clauss, SolidLubricants and Self-Lubricating Solids (1972) at page 1, which isspecifically incorporated by reference herein.

In one embodiment of the invention, the particles 18 can have a lamellarstructure. Particles having a lamellar structure can be composed ofsheets or plates of atoms in hexagonal array, with strong bonding withinthe sheet and weak van der Waals bonding between sheets, providing lowshear strength between sheets. A nonlimiting example of a lamellarstructure is a hexagonal crystal structure. K. Ludema, Friction, Wear,Lubrication (1996) at page 125, Solid Lubricants and Self-LubricatingSolids at pages 19-22, 42-54, 75-77, 80-81, 82, 90-102, 113-120 and 128;and W. Campbell, “Solid Lubricants”, Boundary Lubrication; An Appraisalof World Literature, ASME Research Committee on Lubrication (1969) atpages 202-203, which are specifically incorporated by reference herein.Inorganic solid particles having a lamellar fullerene (buckyball)structure are also useful in the present invention.

Nonlimiting examples of suitable materials having a lamellar structurethat are useful in forming the particles 18 of the present inventioninclude boron nitride, graphite, metal dichalcogenides, mica, talc,gypsum, kaolinite, calcite, cadmium iodide, silver sulfide, and mixturesof any of the foregoing. Such materials include, but are not limited to,boron nitride, graphite, metal dichalcogenides, and mixtures of any ofthe foregoing. Suitable metal dichalcogenides include, but are notlimited to, molybdenum disulfide, molybdenum diselenide, tantalumdisulfide, tantalum diselenide, tungsten disulfide, tungsten diselenide,and mixtures of any of the foregoing.

In one embodiment, the particles 18 can be formed from an inorganicsolid lubricant material having a lamellar structure. A nonlimitingexample of an inorganic solid lubricant material having a lamellarstructure for use in the coating composition of the present invention isboron nitride, such as boron nitride having a hexagonal crystalstructure. Particles formed from boron nitride, zinc sulfide andmontmorillonite also provide good whiteness in composites with polymericmatrix materials such as nylon 6,6.

Nonlimiting examples of particles formed from boron nitride that can besuitable for use in the present invention are POLARTHERM® 100 Series (PT120, PT 140, PT 160 and PT 180); 300 Series (PT 350) and 600 Series (PT620, PT 630, PT 640 and PT 670) boron nitride powder particles,commercially available from Advanced Ceramics Corporation of Lakewood,Ohio. “PolarTherm® Thermally Conductive Fillers for PolymericMaterials”, a technical bulletin of Advanced Ceramics Corporation ofLakewood, Ohio (1996), which is specifically incorporated by referenceherein. These particles have a thermal conductivity of 250-300 Watts permeter ° K at 25° C., a dielectric constant of 3.9 and a volumeresistivity of 10¹⁵ ohm-centimeters. The 100 Series powder particleshave a reported average particle size ranging from 5 to 14 micrometers,the 300 Series powder particles have a reported average particle sizeranging from 100 to 150 micrometers and the 600 Series powder particleshave a reported average particle size ranging from 16 to greater than200 micrometers. In particular, as reported by its supplier, POLARTHERM160 particles have an average particle size of 6 to 12 micrometers, aparticle size range of submicrometer to 70 micrometers, and a particlesize distribution as follows:

% > 10 50 90 Size (μm) 18.4 7.4 0.6

According to this distribution, ten percent of the POLARTHERM® 160 boronnitride particles that were measured had an average particle sizegreater than 18.4 micrometers. As used herein, the “average particlesize” refers to the mean particle size of the particles.

The average particle size of the particles according to the presentinvention can be measured according to known laser scatteringtechniques. In one embodiment of the present invention, the particlessize can be measured using a Beckman Coulter LS 230 laser diffractionparticle size instrument, which uses a laser beam with a wave length of750 nm to measure the size of the particles and assumes the particle hasa spherical shape, i.e., the “particle size” refers to the smallestsphere that will completely enclose the particle. For example, particlesof a sample of POLARTHERM® 160 boron nitride particles measured usingthe Beckman Coulter LS 230 particle size analyzer were found to have anaverage particle size was 11.9 micrometers with particles ranging fromsubmicrometer to 35 micrometers and having the following distribution ofparticles:

% > 10 50 90 Size (μm) 20.6 11.3 4.0

According to this distribution, ten percent of the POLARTHERM® 160 boronnitride particles that were measured had an average particle sizegreater than 20.6 micrometers.

In another embodiment of the present invention, the particles 18 can beformed from inorganic materials that are non-hydratable. As used herein,“non-hydratable” means that the inorganic particles do not react withmolecules of water to form hydrates and do not contain water ofhydration or water of crystallization. A “hydrate” is produced by thereaction of molecules of water with a substance in which the H—OH bondis not split. See R. Lewis, Sr., Hawley's Condensed Chemical Dictionary,(12th Ed. 1993) at pages 609-610 and T. Perros, Chemistry, (1967) atpages 186-187, which are specifically incorporated by reference herein.In the formulas of hydrates, the addition of the water molecules isconventionally indicated by a centered dot, e.g., 3MgO.4SiO₂.H₂O (talc),Al₂O₃.2SiO₂.2H₂O (kaolinite). Structurally, hydratable inorganicmaterials include, but are not limited to, at least one hydroxyl groupwithin a layer of a crystal lattice (but not including hydroxyl groupsin the surface planes of a unit structure or materials which absorbwater on their surface planes or by capillary action), for example asshown in the structure of kaolinite given in FIG. 3.8 at page 34 of J.Mitchell, Fundamentals of Soil Behavior (1976) and as shown in thestructure of 1:1 and 2:1 layer minerals shown in FIGS. 18 and 19,respectively, of H. van Olphen, Clay Colloid Chemistry, (2d Ed. 1977) atpage 62, which are specifically incorporated by reference herein. A“layer” of a crystal lattice is a combination of sheets, which is acombination of planes of atoms. (See Minerals in Soil Environments, SoilScience Society of America (1977) at pages 196-199, which isspecifically incorporated by reference herein). The assemblage of alayer and interlayer material (such as cations) is referred to as a unitstructure.

Hydrates contain coordinated water, which coordinates the cations in thehydrated material and cannot be removed without the breakdown of thestructure, and/or structural water, which occupies interstices in thestructure to add to the electrostatic energy without upsetting thebalance of charge. R. Evans, An Introduction to Crystal Chemistry (1948)at page 276, which is specifically incorporated by reference herein.Generally, the coating compositions contain no more than 50 weightpercent hydratable particles. In one embodiment of the presentinvention, the coating composition can be essentially free of hydratableparticles. As used herein, the term “essentially free of hydratableparticles” means the coating composition comprises less than 20 weightpercent of hydratable particles on a total solids basis, such as, forexample, less than 5 weight percent, and less than 0.001 weight percent.In one embodiment of the present invention, the particles 18 can beformed from a non-hydratable, inorganic solid lubricant material.

The coating compositions according to the present invention can containparticles formed from hydratable or hydrated inorganic materials in lieuof or in addition to the non-hydratable inorganic materials discussedabove. Nonlimiting examples of such hydratable inorganic materialsinclude clay mineral phyllosilicates, including micas (such asmuscovite), talc, montmorillonite, kaolinite and gypsum. As explainedabove, particles formed from such hydratable or hydrated materialsgenerally constitute no more than 50 weight percent of the particles inthe coating composition.

In another embodiment of the present invention, the particles 18 can beformed from non-polymeric, organic materials. Examples of non-polymeric,organic materials useful in the present invention include, but are notlimited to, stearates (such as zinc stearate and aluminum stearate),carbon black and stearamide.

In yet another embodiment of the present invention, the particles 18 canbe formed from inorganic polymeric materials. Nonlimiting examples ofuseful inorganic polymeric materials include polyphosphazenes,polysilanes, polysiloxane, polygeremanes, polymeric sulfur, polymericselenium, silicones, and mixtures of any of the foregoing. A specificnonlimiting example of a particle formed from an inorganic polymericmaterial suitable for use in the present invention is TOSPEARL⁴, whichis a particle formed from cross-linked siloxanes and is commerciallyavailable from Toshiba Silicones Company, Ltd. of Japan.

⁴ See R. J. Perry “Applications for Cross-Linked Siloxane Particles”Chemtech, February 1999 at pages 39-44.

In still another embodiment of the present invention, the particles 18can be formed from synthetic, organic polymeric materials. Suitableorganic polymeric materials include, but are not limited to,thermosetting materials and thermoplastic materials. Suitablethermosetting materials include, but are not limited to, thermosettingpolyesters, vinyl esters, epoxy materials, phenolics, aminoplasts,thermosetting polyurethanes, and mixtures of any of the foregoing. Aspecific, nonlimiting example of a synthetic polymeric particle formedfrom an epoxy material is an epoxy microgel particle.

Suitable thermoplastic materials include, but are not limited to,thermoplastic polyesters, polycarbonates, polyolefins, acrylic polymers,polyamides, thermoplastic polyurethanes, vinyl polymers, and mixtures ofany of the foregoing. Suitable thermoplastic polyesters include, but arenot limited to, polyethylene terephthalate, polybutylene terephthalateand polyethylene naphthalate. Suitable polyolefins include, but are notlimited to, polyethylene, polypropylene and polyisobutene. Suitableacrylic polymers include, but are not limited to, copolymers of styreneand an acrylic monomer and polymers containing methacrylate. Nonlimitingexamples of synthetic polymeric particles formed from an acryliccopolymer include RHOPLEX® B-85⁵, which is an opaque, non-crosslinkingsolid acrylic particle emulsion, ROPAQUE® HP-1055⁶, which is an opaque,non-film-forming, styrene acrylic polymeric synthetic pigment having a1.0 micrometer particle size, a solids content of 26.5 percent by weightand a 55 percent void volume, ROPAQUE® OP-96⁷ and ROPAQUE® HP-543P⁸,which are identical, each being an opaque, non-film-forming, styreneacrylic polymeric synthetic pigment dispersion having a particle size of0.55 micrometers and a solids content of 30.5 percent by weight, andROPAQUE® OP-62 LO⁹ which is also an opaque, non-film-forming, styreneacrylic polymeric synthetic pigment dispersion having a particles sizeof 0.40 micrometers and a solids content of 36.5 percent by weight. Eachof these specific particles is commercially available from Rohm and HaasCompany of Philadelphia, Pa.

⁵ See “Chemicals for the Textile Industry” September 1987, availablefrom Rohm and Haas Company, Philadelphia, Pa.

⁶ See product property sheet entitled: “ROPAQUE® HP-1055, Hollow SpherePigment for Paper and Paperboard Coatings” October 1994, available fromRohm and Haas Company, Philadelphia, Pa. at page 1, which is herebyincorporated by reference.

⁷ See product technical bulletin entitled: “ArchitecturalCoatings—ROPAQUE® OP-96, The All Purpose Pigment”, April 1997 availablefrom Rohm and Haas Company, Philadelphia, Pa. at page 1 which is herebyincorporated by reference.

⁸ ROPAQUE® HP-543P and ROPAQUE® OP-96 are the same material; thematerial is identified as ROPAQUE® HP-543P in the paint industry and asROPAQUE® OP-96 in the coatings industry.

⁹ See product technical bulletin entitled: “ArchitecturalCoatings—ROPAQUE® OP-96, The All Purpose Pigment”, April 1997 availablefrom Rohm and Haas Company, Philadelphia, Pa. at page 1, which is herebyincorporated by reference.

The particles 18 according to the present invention can also be formedfrom semisynthetic, organic polymeric materials and natural polymericmaterials. As used herein, a “semisynthetic material” is a chemicallymodified, naturally occurring material. Suitable semisynthetic, organicpolymeric materials from which the particles 18 can be formed include,but are not limited to, cellulosics, such as methylcellulose andcellulose acetate; and modified starches, such as starch acetate andstarch hydroxyethyl ethers. Suitable natural polymeric materials fromwhich the particles 18 can be formed include, but are not limited to,polysaccharides, such as starch; polypeptides, such as casein; andnatural hydrocarbons, such as natural rubber and gutta percha.

In one embodiment of the present invention, the polymeric particles 18can be formed from hydrophobic polymeric materials to reduce or limitmoisture absorption by the coated strand. Nonlimiting examples of suchhydrophobic polymeric materials include, but are not limited to,polyethylene, polypropylene, polystyrene and polymethylmethacrylate.Nonlimiting examples of polystyrene copolymers include ROPAQUE® HP-1055,ROPAQUE® OP-96, ROPAQUE® HP-543P, and ROPAQUE® OP-62 LO pigments (eachdiscussed above).

In another embodiment of the present invention, polymeric particles 18can be formed from polymeric materials having a glass transitiontemperature (T_(g)) and/or melting point greater than 25° C. such asgreater than 50° C.

In still another embodiment of the present invention, the particles 18can be hollow particles formed from materials selected from polymericand non-polymeric inorganic materials, polymeric and non-polymericorganic materials, composite materials, and mixtures of any of theforegoing. Nonlimiting examples of suitable materials from which thehollow particles can be formed are described above. Nonlimiting examplesof a hollow polymeric particle useful in present invention includeROPAQUE® HP-1055, ROPAQUE® OP-96, ROPAQUE® HP-543P, and ROPAQUE® OP-62LO pigments (each discussed above). For other nonlimiting examples ofhollow particles that can be useful in the present invention see H. Katzet al. (Ed.) (1987) at pages 437-452, which are specificallyincorporated by reference herein.

The particles 18 useful in the coating composition present invention canbe present in a dispersion, suspension or emulsion in water. Othersolvents, such as mineral oil or alcohol (generally less than 5 weightpercent), can be included in the dispersion, suspension or emulsion, ifdesired. A nonlimiting example of a dispersion of particles formed froman inorganic material is ORPAC BORON NITRIDE RELEASECOAT-CONC, which isa dispersion of 25 weight percent boron nitride particles in water andis commercially available from ZYP Coatings, Inc. of Oak Ridge, Tenn.“ORPAC BORON NITRIDE RELEASECOAT-CONC”, a technical bulletin of ZYPCoatings, Inc., is specifically incorporated by reference herein.According to this technical bulletin, the boron nitride particles inthis product have an average particle size of less than 3 micrometersand include 1 percent of magnesium-aluminum silicate to bind the boronnitride particles to the substrate to which the dispersion is applied.Independent testing of a sample of ORPAC BORON NITRIDE RELEASECOAT-CONC25 boron nitride using the Beckman Coulter LS 230 particle size analyzerfound an average particle size of 6.2 micrometers, with particlesranging from submicrometer to 35 micrometers and having the followingdistribution of particles:

% > 10 50 90 Size (μm) 10.2 5.5 2.4

According to this distribution, ten percent of the ORPAC BORON NITRIDERELEASECOAT-CONC 25 boron nitride particles that were measured had anaverage particle size greater than 10.2 micrometers.

Other useful products which are commercially available from ZYP Coatingsinclude BORON NITRIDE LUBRICOAT® paint, and BRAZE STOP and WELD RELEASEproducts. Specific, nonlimiting examples of emulsions and dispersions ofsynthetic polymeric particles formed from acrylic polymers andcopolymers include: RHOPLEX® B-85 acrylic emulsion (discussed above),RHOPLEX® GL-623¹⁰ which is an all acrylic firm polymer emulsion having asolids content of 45 percent by weight and a glass transitiontemperature of 98° C.; EMULSION E-2321¹¹ which is a hard, methacrylatepolymer emulsion having a solids content of 45 percent by weight and aglass transition temperature of 105° C.; ROPAQUE® OP-96 and ROPAQUE®HP-543P (discussed above), which are supplied as a dispersion having aparticle size of 0.55 micrometers and a solids content of 30.5 percentby weight; ROPAQUE® OP-62 LO (discussed above), which is supplied as adispersion having a particles size of 0.40 micrometers and a solidscontent of 36.5 percent by weight; and ROPAQUE® HP-1055 (discussedabove), which is supplied as a dispersion having a solids content of26.5 percent by weight; all of which are commercially available fromRohm and Haas Company of Philadelphia, Pa.

¹⁰ See product property sheet entitled: “Rhoplex® GL-623,Self-Crosslinking Acrylic Binder of Industrial Nonwovens”, March 1997available from Rohm and Haas Company, Philadelphia, Pa., which is herebyincorporated by reference.

¹¹ See product property sheet entitled: “Building Products IndustrialCoatings-Emulsion E-2321”, 1990, available from Rohm and Haas Company,Philadelphia, Pa., which is hereby incorporated by reference.

In one embodiment of the present invention, the coating compositioncomprises a mixture of at least one inorganic particle, particularlyboron nitride, and more particularly a boron nitride available under thetradename POLARTHERM® and/or ORPAC BORON NITRIDE RELEASECOAT-CONC, andat least one thermoplastic material, particularly a copolymer of styreneand an acrylic monomer, and more particularly a copolymer availableunder the tradename ROPAQUE®.

The particles 18 can be selected to achieve an average particle size 19sufficient to effect the desired spacing between adjacent fibers. Forexample, the average size 19 of the particles 18 incorporated into asizing composition applied to fibers 12 to be processed on air-jet loomscan be selected to provide sufficient spacing between at least twoadjacent fibers to permit air-jet transport of the fiber strand 10across the loom. As used herein, “air-jet loom” means a type of loom inwhich the fill yarn (weft) is inserted into the warp shed by a blast ofcompressed air from one or more air jet nozzles in a manner well knownto those skilled in the art. In another example, the average size 19 ofthe particles 18 incorporated into a sizing composition applied tofibers 12 to be impregnated with a polymeric matrix material can beselected to provide sufficient spacing between at least two adjacentfibers to permit good wet-out and wet-through of the fiber strand 10.

Although not limiting in the present invention, in one embodiment theparticles 18 can have an average size, measured using laser scatteringtechniques, of no greater than 1000 micrometers. In another embodiment,the particle can have an average particle size, measured using laserscattering techniques, of 0.001 to 100 micrometers. In anotherembodiment, the particles can have an average size, measured using laserscattering techniques, of 0.1 to 25 micrometers.

In another embodiment of the present invention, the average particlesize 19 of the particles 18, measured using laser scattering techniques,can be at least 0.1 micrometers, and in one embodiment can be at least0.5 micrometers. In still another embodiment, the average particle size19 of particle 18, measured using laser scattering techniques, can rangefrom 0.1 micrometers to 10 micrometers, such as, for example, from 0.1micrometers to 5 micrometers, from 0.5 micrometers to 2 micrometers. Inanother embodiment of the present invention, the particles 18 can havean average particle size 19 that is generally smaller than the averagediameter of the fibers 12 to which the coating composition is applied.It has been observed that twisted yarns made from fiber strands 10having a layer 14 of a residue of a primary sizing compositioncomprising particles 18 having average particles sizes 19 discussedabove can advantageously provide sufficient spacing between adjacentfibers 23, 25 to permit air-jet weavability (i.e., air-jet transportacross the loom) while maintaining the integrity of the fiber strand 10and providing acceptable wet-through and wet-out characteristics whenimpregnated with a polymeric matrix material.

In another embodiment of the present invention, the average particlessize 19 of particles 18, measured using laser scattering techniques, canbe at least 3 micrometers and can range from 3 to 1000 micrometers. Instill another embodiment, the average particles size 19 of particles 18,measured using laser scattering techniques, can be at least 5micrometers and can range from 5 to 1000 micrometers. In anotherembodiment of the present invention, the average particles size 19 ofparticles 18, measured using laser scattering techniques, can range from10 to 25 micrometers. In this embodiment the average particle size 19 ofthe particles 18 can correspond generally to the average nominaldiameter of the glass fibers. It has been observed that fabrics madewith strands coated with particles falling within the sizes discussedabove exhibit good wet-through and wet-out characteristics whenimpregnated with a polymeric matrix material.

It will be recognized by one skilled in the art that mixtures of one ormore particles 18 having different average particle sizes 19 can beincorporated into the coating composition in accordance with the presentinvention to impart the desired properties and processingcharacteristics to the fiber strands 10 and to the products subsequentlymade therefrom. More specifically, different sized particles can becombined in appropriate amounts to provide strands having good air-jettransport properties as well to provide a fabric exhibiting good wet-outand wet-through characteristics.

Fibers can be subject to abrasive wear by contact with asperities ofadjacent fibers and/or other solid objects or materials which the glassfibers contact during forming and subsequent processing, such as weavingor roving. “Abrasive wear”, as used herein, means scraping or cuttingoff of bits of the fiber surface or breakage of fibers by frictionalcontact with particles, edges or entities of materials which can be hardenough to produce damage to the fibers. See K. Ludema at page 129, whichis specifically incorporated by reference herein. Abrasive wear of fiberstrands causes detrimental effects to the fiber strands, such as strandbreakage during processing and surface defects in products such as wovencloth and composites, which increases waste and manufacturing cost.

In the forming step, for example, fibers, particularly glass fibers,contact solid objects such as a metallic gathering shoe and a traverseor spiral before being wound into a forming package. In fabric assemblyoperations, such as knitting or weaving, the glass fiber strand contactssolid objects such as portions of the fiber assembly apparatus (e.g. aloom or knitting device) which can abrade the surfaces 16 of thecontacting glass fibers 12. Examples of portions of a loom which contactthe glass fibers include, but are not limited to, air jets and shuttles.Surface asperities of these solid objects that have a hardness valuegreater than that of the glass fibers can cause abrasive wear of theglass fibers. For example, many portions of the twist frame, loom andknitting device are formed from metallic materials such as steel, whichhas a Mohs' hardness up to 8.5¹². Abrasive wear of glass fiber strandsfrom contact with asperities of these solid objects causes strandbreakage during processing and surface defects in products such as wovencloth and composites, which increases waste and manufacturing cost.

¹² Handbook of Chemistry and Physics at page F-22.

To minimize abrasive wear, in one embodiment of the present invention,the particles 18 can have a hardness value which does not exceed, i.e.,is less than or equal to, a hardness value of the glass fiber(s). Thehardness values of the particles and glass fibers can be determined byany conventional hardness measurement method, such as Vickers or Brinellhardness, or can be determined according to the original Mohs' hardnessscale which indicates the relative scratch resistance of the surface ofa material on a scale of one to ten. The Mohs' hardness value of glassfibers generally ranges from 4.5 to 6.5, and is generally 6. R. Weast(Ed.), Handbook of Chemistry and Physics, CRC Press (1975) at page F-22,which is specifically incorporated by reference herein. In thisembodiment, the Mohs' hardness value of the particles 18 can range from0.5 to 6. The Mohs' hardness values of several nonlimiting examples ofparticles formed from inorganic materials suitable for use in thepresent invention are given in Table A below.

TABLE A Particle material Mohs' hardness (original scale) boron nitride2¹³ graphite 0.5-1¹⁴ molybdenum disulfide 1¹⁵ talc 1-1.5¹⁶ mica2.8-3.2¹⁷ kaolinite 2.0-2.5¹⁸ gypsum 1.6-2¹⁹ calcite (calcium carbonate)3²⁰ calcium fluoride 4²¹ zinc oxide 4.5²² aluminum 2.5²³ copper 2.5-3²⁴iron 4-5²⁵ gold 2.5-3²⁶ nickel 5²⁷ palladium 4.8²⁸ platinum 4.3²⁹ silver2.5-4³⁰ zinc sulfide 3.5-4³¹ ¹³K. Ludema, Friction, Wear, Lubrication,(1996) at page 27, which is hereby incorporated by reference. ¹⁴R.Wearst (Ed.), Handbook of Chemistry and Physics, CRC Press (1975) atpage F-22. ¹⁵R. Lewis, Sr., Hawley's Condensed Chemical Dictionary,(12th Ed. 1993) at page 793, which is hereby incorporated by reference.¹⁶ Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at page 1113,which is hereby incorporated by reference. ¹⁷ Hawley's CondensedChemical Dictionary, (12th Ed. 1993) at page 784, which is herebyincorporated by reference. ¹⁸ Handbook of Chemistry and Physics at pageF-22. ¹⁹ Handbook of Chemistry and Physics at page F-22. ²⁰ Friction,Wear, Lubrication at page 27. ²¹ Friction, Wear, Lubrication at page 27.²² Friction, Wear, Lubrication at page 27. ²³ Friction, Wear,Lubrication at page 27. ²⁴ Handbook of Chemistry and Physics at pageF-22. ²⁵ Handbook of Chemistry and Physics at page F-22. ²⁶ Handbook ofChemistry and Physics at page F-22. ²⁷ Handbook of Chemistry and Physicsat page F-22. ²⁸ Handbook of Chemistry and Physics at page F-22. ²⁹Handbook of Chemistry and Physics at page F-22. ³⁰ Handbook of Chemistryand Physics at page F-22. ³¹R. Weast (Ed.), Handbook of Chemistry andPhysics, CRC Press (71^(st) Ed. 1990) at page 4-158.

As mentioned above, the Mohs' hardness scale relates to the resistanceof a material to scratching. The instant invention therefore furthercontemplates particles that have a hardness at their surface that isdifferent from the hardness of the internal portions of the particlebeneath its surface. More specifically, and as discussed above, thesurface of the particle can be modified in any manner well known in theart, including, but not limited to, chemically changing the particle'ssurface characteristics using techniques known in the art such that thesurface hardness of the particle can be less than or equal to thehardness of the glass fibers while the hardness of the particle beneaththe surface can be greater than the hardness of the glass fibers. Asanother alternative, a particle can be formed from a primary materialthat is coated, clad or encapsulated with one or more secondarymaterials to form a composite material that has a softer surface.Alternatively, a particle can be formed from a primary material that iscoated, clad or encapsulated with a differing form of the primarymaterial to form a composite material that has a softer surface.

In one example, and without limiting the present invention, an inorganicparticle formed from an inorganic material such as silicon carbide oraluminum nitride can be provided with a silica, carbonate or nanoclaycoating to form a useful composite particle. In another embodiment, theinorganic particles can be reacted with a coupling agent havingfunctionality capable of covalently bonding to the inorganic particlesand functionality capable of crosslinking into the film-forming materialor crosslinkable resin. Such coupling agents are described in U.S. Pat.No. 5,853,809 at column 7, line 20 through column 8, line 43, which isincorporated herein by reference. Useful silane coupling agents include,but are not limited to, glycidyl, isocyanato, amino or carbamylfunctional silane coupling agents. In another nonlimiting example, asilane coupling agent with alkyl side chains can be reacted with thesurface of an inorganic particle formed from an inorganic oxide toprovide a useful composite particle having a “softer” surface. Otherexamples include, but are not limited to, cladding, encapsulating orcoating particles formed from non-polymeric or polymeric materials withdiffering non-polymeric or polymeric materials. A specific nonlimitingexample of such composite particles is DUALITE, which is a syntheticpolymeric particle coated with calcium carbonate that is commerciallyavailable from Pierce and Stevens Corporation of Buffalo, N.Y.

In one embodiment of the present invention, the particles 18 can bethermally conductive, i.e., the particles have a thermal conductivity ofat least 0.2 Watts per meter K, such as, for example, at least 0.5 Wattsper meter K, measured at a temperature of 300K. In one embodiment, theparticles 18 can have a thermal conductivity of at least 1 Watt permeter K, such as at least 5 Watts per meter K, measured at a temperatureof 300K. In another embodiment, the thermal conductivity of theparticles can be at least 25 Watts per meter K, such as, for example, atleast 30 Watts per meter K, and at least 100 Watts per meter K, measuredat a temperature of 300K. In another embodiment, the thermalconductivity of the particles can range from 5 to 2000 Watts per meterK, such as, for example, from 25 to 2000 Watts per meter K, from 30 to2000 Watts per meter K, and from 100 to 2000 Watts per meter K, measuredat a temperature of 300K. As used herein, “thermal conductivity” meansthe property of the particle that describes its ability to transfer heatthrough itself. See R. Lewis, Sr., Hawley's Condensed ChemicalDictionary, (12th Ed. 1993) at page 305, which is specificallyincorporated by reference herein.

The thermal conductivity of a material can be determined by any methodknown to one skilled in the art. For example, if the thermalconductivity of the material to be tested ranges from 0.001 Watts permeter K to 100 Watts per meter K, the thermal conductivity of thematerial can be determined using the guarded hot plate method accordingto ASTM C-177-85 (which is specifically incorporated by referenceherein) at a temperature of 300K . If the thermal conductivity of thematerial to be tested ranges from 20 Watts per meter K to 1200 Watts permeter K, the thermal conductivity of the material can be determinedusing the guarded hot flux sensor method according to ASTM C-518-91(which is specifically incorporated by reference herein). In otherwords, the guarded hot plate method is to be used if the thermalconductivity ranges from 0.001 Watts per meter K to 20 Watts per meterK. If the thermal conductivity is over 100 Watts per meter K, theguarded hot flux sensor method is to be used. For ranges from 20 to 100Watts per meter K, either method can be used.

In the guarded hot plate method, a guarded hot plate apparatuscontaining a guarded heating unit, two auxiliary heating plates, twocooling units, edge insulation, a temperature controlled secondaryguard, and a temperature sensor read-out system is used to test twoessentially identical samples. The samples can be placed on either sideof the guarded heating unit with the opposite faces of the specimens incontact with the auxiliary heating units. The apparatus is then heatedto the desired test temperature and held for a period of time requiredto achieve thermal steady state. Once the steady state condition isachieved, the heat flow (Q) passing through the samples and thetemperature difference (ΔT) across the samples are recorded. The averagethermal conductivity (KTC) of the samples is then calculated using thefollowing formula (I):

K _(TC) =QL/A·ΔT  (I)

wherein L is the average thickness of the samples and A is the averageof the combined area of the samples.

It is believed that the materials with higher thermal conductivity willmore quickly dissipate the heat generated during a drilling operationfrom the hole area, resulting in prolonged drill tip life. The thermalconductivity of selected material in Table A is included in Table B.

Although not required, in another embodiment useful in the presentinvention, the particles can be electrically insulative or have highelectrical resistivity, i.e., have an electrical resistivity greaterthan 1000 microohm-cm. Use of particles having high electricalresistivity for conventional electronic circuit board applications caninhibit loss of electrical signals due to conduction of electronsthrough the reinforcement. For specialty applications, such as circuitboards for microwave, radio frequency interference and electromagneticinterference applications, particles having high electrical resistivityare not required. The electrical resistance of selected materials inTable A is included in Table B.

TABLE B Electrical Resistance Inorganic Solid Thermal conductivity(microohm- Mohs' hardness Material (W/m K at 300 K.) centimeters)(original scale) boron nitride  200³²  1.7 × 10¹⁹ ³³  2³⁴ boronphosphide  350³⁵ —  9.5³⁶ aluminum phosphide  130³⁷ — — aluminum nitride 200³⁸ greater than 10¹⁹ ³⁹  9⁴⁰ gallium nitride  170⁴¹ — — galliumphosphide  100⁴² — — silicon carbide  270⁴³  4 × 10⁵ greater than 9⁴⁵ to1 × 10⁶ ⁴⁴ silicon nitride  30⁴⁶ 10¹⁹ to 10²⁰ ⁴⁷  9⁴⁸ beryllium oxide 240⁴⁹ —  9⁵⁰ zinc oxide  26 —  4.5⁵¹ zinc sulfide  25⁵²  2.7 × 10⁵ 3.5-4⁵⁴ to 1.2 × 10¹² ⁵³ diamond 2300⁵⁵  2.7 × 10⁸ ⁵⁶ 10⁵⁷ silicon 84⁵⁸  10.0⁵⁹  7⁶⁰ graphite up to 2000⁶¹ 100⁶²  0.5-1⁶³ molybdenum 138⁶⁴  5.2⁶⁵  5.5⁶⁶ platinum  69⁶⁷  10.6⁶⁸  4.3⁶⁹ palladium  70⁷⁰ 10.8⁷¹  4.8⁷² tungsten  200⁷³  5.5⁷⁴  7.5⁷⁵ nickel  92⁷⁶  6.8⁷⁷  5⁷⁸aluminum  205⁷⁹  4.3⁸⁰  2.5⁸¹ chromium  66⁸²  20⁸³  9.0⁸⁴ copper  398⁸⁵ 1.7⁸⁶  2.5-3⁸⁷ gold  297⁸⁸  2.2⁸⁹  2.5-3⁹⁰ iron  74.5⁹¹  9⁹²  4-5⁹³silver  418⁹⁴  1.6⁹⁵  2.5-4⁹⁶ ³²G. Slack, “Nonmetallic Crystals withHigh Thermal Conductivity, J. Phys. Chem. Solids (1973) Vol. 34, p. 322,which is hereby incorporated by reference. ³³A. Weimer (Ed.), Carbide,Nitride and Boride Materials Synthesis and Processing, (1997) at page654. ³⁴Friction, Wear, Lubrication at page 27. ³⁵G. Slack, “NonmetallicCrystals with High Thermal Conductivity, J. Phys. Chem. Solids (1973)Vol. 34, p. 325, which is hereby incorporated by reference. ³⁶R. Lewis,Sr., Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at page164, which is hereby incorporated by reference. ³⁷G. Slack, “NonmetallicCrystals with High Thermal Conductivity, J. Phys. Chem. Solids (1973)Vol. 34, p. 333, which is hereby incorporated by reference. ³⁸G. Slack,“Nonmetallic Crystals with High Thermal Conductivity, J. Phys. Chem.Solids (1973) Vol. 34, p. 329, which is hereby incorporated byreference. ³⁹A. Weimer (Ed.), Carbide, Nitride and Boride MaterialsSynthesis and Processing, (1997) at page 654. ⁴⁰Friction, Wear,Lubrication at page 27. ⁴¹G. Slack, “Nonmetallic Crystals with HighThermal Conductivity, J. Phys. Chem. Solids (1973) Vol. 34, p. 333 ⁴²G.Slack, “Nonmetallic Crystals with High Thermal Conductivity, J. Phys.Chem. Solids (1973) Vol. 34, p. 321, which is hereby incorporated byreference. ⁴³Microelectronics Packaging Handbook at page 36, which ishereby incorporated by reference. ⁴⁴A. Weimer (Ed.), Carbide, Nitrideand Boride Materials Synthesis and Processing, (1997) at page 653, whichis hereby incorporated by reference. ⁴⁵Friction, Wear, Lubrication atpage 27. ⁴⁶Microelectronics Packaging Handbook at page 36, which ishereby incorporated by reference. ⁴⁷A. Weimer (Ed.), Carbide, Nitrideand Boride Materials Synthesis and Processing, (1997) at page 654.⁴⁸Friction, Wear, Lubrication at page 27. ⁴⁹Microelectronics PackagingHandbook at page 905, which is hereby incorporated by reference.⁵⁰Hawley's Condensed Chemical Dictionary, (12th Ed. 1993) at page 141,which is hereby incorporated by reference. ⁵¹Friction, Wear, Lubricationat page 27. ⁵²Handbook of Chemistry and Physics, CRC Press (1975) atpages 12-54. ⁵³Handbook of Chemistry and Physics, CRC Press (71st Ed.1990) at pages 12-63, which is hereby incorporated by reference.⁵⁴Handbook of Chemistry and Physics, CRC Press (71st Ed. 1990) at pages4-158, which is hereby incorporated by reference. ⁵⁵MicroelectronicsPackaging Handbook at page 36. ⁵⁶Handbook of Chemistry and Physics, CRCPress (71st Ed. 1990) at pages 12-63, which is hereby incorporated byreference. ⁵⁷Handbook of Chemistry and Physics, CRC Press (71st Ed.1990) at page F-22. ⁵⁸Microelectronics Packaging Handbook at page 174.⁵⁹Handbook of Chemistry and Physics at page F-166, which is herebyincorporated by reference. ⁶⁰Friction, Wear, Lubrication at page 27.⁶¹G. Slack, “Nonmetallic Crystals with High Thermal Conductivity, J.Phys. Chem. Solids (1973) Vol. 34, p. 322, which is hereby incorporatedby reference. ⁶²See W. Callister, Materials Science and Engineering AnIntroduction, (2d ed. 1991) at page 637, which is hereby incorporated byreference. ⁶³Handbook of Chemistry and Physics at page F-22.⁶⁴Microelectronics Packaging Handbook at page 174. ⁶⁵MicroelectronicsPackaging Handbook at page 37. ⁶⁶According to “Web Elements”http://www.shef.ac.uk/˜chem/web-elents/nofr-image-l/hardness-minerals-l.html(February 26, 1998). ⁶⁷Microelectronics Packaging Handbook at page 174.⁶⁸Microelectronics Packaging Handbook at page 37. ⁶⁹Handbook ofChemistry and Physics at page F-22. ⁷⁰Microelectronics PackagingHandbook at page 37. ⁷¹Microelectronics Packaging Handbook at page 37.⁷²Handbook of Chemistry and Physics at page F-22. ⁷³MicroelectronicsPackaging Handbook at page 37. ⁷⁴Microelectronics Packaging Handbook atpage 37. ⁷⁵According to “Web Elements”http://www.shef.ac.uk/˜chem/web-elents/nofr-image-l/hardness-minerals-l.html(February 26, 1998) ⁷⁶Microelectronics Packaging Handbook at page 174.⁷⁷Microelectronics Packaging Handbook at page 37. ⁷⁸Handbook ofChemistry and Physics at page F-22. ⁷⁹Microelectronics PackagingHandbook at page 174. ⁸⁰Microelectronics Packaging Handbook at page 37.⁸¹Friction, Wear, Lubrication at page 27. ⁸²Microelectronics PackagingHandbook at page 37. ⁸³Microelectronics Packaging Handbook at page 37.⁸⁴Handbook of Chemistry and Physics at page F-22. ⁸⁵MicroelectronicsPackaging Handbook at page 174. ⁸⁶Microelectronics Packaging Handbook atpage 37. ⁸⁷Handbook of Chemistry and Physics at page F-22.⁸⁸Microelectronics Packaging Handbook at page 174. ⁸⁹MicroelectronicsPackaging Handbook at page 37. ⁹⁰Handbook of Chemistry and Physics atpage F-22. ⁹¹Microelectronics Packaging Handbook at page 174. ⁹²Handbookof Chemistry and Physics, CRC Press (1975) at page D-171, which ishereby incorporated by reference. ⁹³Handbook of Chemistry and Physics atpage F-22. ⁹⁴Microelectronics Packaging Handbook at page 174.⁹⁵Microelectronics Packaging Handbook at page 37. ⁹⁶Handbook ofChemistry and Physics at page F-22.

It will be appreciated by one skilled in the art that particles 18 ofthe coating composition of the present invention can include anycombination or mixture of particles 18 discussed above. Morespecifically, and without limiting the present invention, the particles18 can include any combination of additional particles made from any ofthe materials described above. Thus, all particles 18 do not have to bethe same; they can be chemically different and/or chemically the samebut different in configuration or properties. The additional particlescan generally comprise up to half of the particles 18, such as up to 15percent of the particles 18.

In one embodiment, the particles 18 can comprise 0.001 to 99 weightpercent of the coating composition on a total solids basis, such as, forexample, 50 to 99 weight percent, and 75 to 99 weight percent. In thisembodiment, the coatings can include, but are not limited to: i)coatings comprising an organic component and lamellar particles having athermal conductivity of at least 1 Watt per meter K at a temperature of300 K; ii) coatings comprising an organic component and non-hydratable,lamellar particles; iii) coatings comprising at least one boron-freelamellar particle having a thermal conductivity of at least 1 Watt permeter K at a temperature of 300K; iv) a residue of an aqueouscomposition comprising lamellar particles having a thermal conductivityof at least 1 Watt per meter K at a temperature of 300K, i.e., lamellarparticles on the fiber; and v) a residue of an aqueous compositioncomprising alumina-free, non-hydratable particles having a thermalconductivity of at least 1 Watt per meter K at a temperature of 300K,i.e., alumina-free, non-hydratable particles on the fiber.

In another embodiment, the particles 18 can comprise 0.001 to 99 weightpercent of the coating composition on a total solids basis, such as, forexample, from 1 to 80 weight percent, and 1 to 40 weight percent. Inaddition, in the particular embodiment wherein the particles 18 arenon-hydratable inorganic particles, the particles can comprise 1 to 50weight percent of the coating composition on a total solids basis, suchas up to 25 weight percent of the coating composition.

In yet another embodiment, the particles 18 can comprise greater than 20weight percent of the coating composition on a total solids basis, suchas, for example, from 20 to 99 weight percent, from 25 to 80 weightpercent, and from 50 to 60 weight percent. In this embodiment, coatingscan comprise resin compatible coating compositions comprising greaterthan 20 weight percent on a total solids basis of at least one particleselected from inorganic particles, organic hollow particles andcomposite particles, the at least one particle having a Mohs' hardnessvalue which does not exceed the Mohs' hardness value of at least oneglass fiber.

In another embodiment, the particles 18 can comprise 1 to 80 weightpercent of the coating composition on a total solids basis, such as 1 to60 weight percent. In one embodiment, the coating composition contains20 to 60 weight percent of particles 18 on total solids basis, and suchas, for example, 35 to 55 weight percent, and 30 to 50 weight percent.Suitable coatings further to this embodiment can include, but are notlimited to, a resin compatible coating comprising (a) a plurality ofdiscrete particles formed from materials selected from non-heatexpandable organic materials, inorganic polymeric materials, non-heatexpandable composite materials and mixtures thereof, the particleshaving an average particle size sufficient to allow strand wet outwithout application of external heat; (b) at least one lubriciousmaterial different from said plurality of discrete particles; and (c) atleast one film-forming material.

In addition to the particles, the coating composition can comprise oneor more film-forming materials, such as organic, inorganic and naturalpolymeric materials. Useful organic materials include, but are notlimited to, polymeric materials selected from synthetic polymericmaterials, semisynthetic polymeric materials, natural polymericmaterials, and mixtures of any of the foregoing. Synthetic polymericmaterials include, but are not limited to, thermoplastic materials andthermosetting materials. The polymeric film-forming materials can form agenerally continuous film when applied to the surface 16 of the glassfibers.

Generally, the amount of film-forming materials can range from 1 to 99weight percent of the coating composition on a total solids basis. Inone embodiment, the amount of film-forming materials can range from 1 to50 weight percent, such as from 1 to 25 weight percent. In anotherembodiment, the amount of film-forming materials can range from 20 to 99weight percent, such as from 60 to 80 weight percent.

In another embodiment, the amount of film-forming materials can rangefrom 20 to 75 weight percent of the coating composition on a totalsolids basis, such as from 40 to 50 weight percent. In this embodiment,the coatings can comprise a film-forming material and greater than 20weight percent on a total solids basis of at least one particle selectedfrom inorganic particles, organic hollow particles and compositeparticles, the at least one particle having a Mohs' hardness value whichdoes not exceed the Mohs' hardness value of at the least one glassfiber.

In yet another embodiment, the amount of polymeric film-formingmaterials can range from 1 to 60 weight percent of the coatingcomposition on a total solids basis, such as, for example, from 5 to 50weight percent, and from 10 to 30 weight percent. Suitable coatingsfurther to this embodiment can include, but are not limited to, a resincompatible coating comprising (a) a plurality of discrete particlesformed from materials selected from non-heat expandable organicmaterials, inorganic polymeric materials, non-heat expandable compositematerials and mixtures thereof, the particles having an average particlesize sufficient to allow strand wet out without application of externalheat; (b) at least one lubricious material different from said pluralityof discrete particles; and (c) at least one film-forming material.

In one embodiment of the present invention, thermosetting polymericfilm-forming materials can be the polymeric film-forming materials foruse in the coating composition for coating glass fiber strands. Suchmaterials are compatible with thermosetting matrix materials used aslaminates for printed circuit boards, such as FR-4 epoxy resins, whichare polyfunctional epoxy resins and in one particular embodiment of theinvention is a difunctional brominated epoxy resins. See ElectronicMaterials Handbook™, ASM International (1989) at pages 534-537, whichare specifically incorporated by reference herein.

Useful thermosetting materials include, but are not limited to,thermosetting polyesters, epoxy materials, vinyl esters, phenolics,aminoplasts, thermosetting polyurethanes, carbamate-functional polymersand mixtures of any of the foregoing. Suitable thermosetting polyestersinclude, but are not limited to, STYPOL polyesters that are commerciallyavailable from Cook Composites and Polymers of Kansas City, Mo., andNEOXIL polyesters that are commercially available from DSM B.V. of Como,Italy.

A nonlimiting example of a thermosetting polymeric material can be anepoxy material. Useful epoxy materials contain at least one epoxy oroxirane group in the molecule, such as polyglycidyl ethers of polyhydricalcohols or thiols. Examples of suitable epoxy film-forming polymersinclude, but are not limited to, EPON® 826 and EPON® 880 epoxy resins,commercially available from Shell Chemical Company of Houston, Tex.

Useful carbamate-functional polymers include, but are not limited to,carbamate-functional acrylic polymers in which pendent and/or terminalcarbamate functional groups can be incorporated into the acrylic polymerby copolymerizing the acrylic monomer with a carbamate functional vinylmonomer, such as a carbamate functional alkyl ester of methacrylic acid.The carbamate groups can also be incorporated into the acrylic polymerby a “transcarbamoylation” reaction in which a hydroxyl functionalacrylic polymer is reacted with a low molecular weight carbamate derivedfrom an alcohol or a glycol ether. The carbamate groups exchange withthe hydroxyl groups yielding the carbamate functional acrylic polymerand the original alcohol or glycol ether. The carbamate functionalgroup-containing acrylic polymer typically has a Mn ranging from 500 to30,000 and a calculated carbamate equivalent weight typically within therange of 15 to 150 based on equivalents of reactive carbamate groups.

It should be understood that the carbamate functional group-containingpolymers can typically contain residual hydroxyl functional groups whichprovide additional crosslinking sites. In one embodiment, thecarbamate/hydroxyl functional group-containing polymer has a residualhydroxyl value ranging from 0.5 to 10 mg KOH per gram.

Useful thermoplastic polymeric materials include, but are not limitedto, vinyl polymers, thermoplastic polyesters, polyolefins, polyamides(e.g. aliphatic polyamides or aromatic polyamides such as aramid),thermoplastic polyurethanes, acrylic polymers (such as polyacrylicacid), and mixtures of any of the foregoing.

In another embodiment of the present invention, the polymericfilm-forming material can be a vinyl polymer. Useful vinyl polymers inthe present invention include, but are not limited to, polyvinylpyrrolidones such as PVP K-15, PVP K-30, PVP K-60 and PVP K-90, each ofwhich is commercially available from International Specialty ProductsChemicals of Wayne, N.J. Other suitable vinyl polymers include, but arenot limited to, RESYN 2828 and RESYN 1037 vinyl acetate copolymeremulsions which are commercially available from National Starch andChemical of Bridgewater, N.J., other polyvinyl acetates such as arecommercially available from H. B. Fuller and Air Products and ChemicalsCompany of Allentown, Pa., and polyvinyl alcohols which are alsoavailable from Air Products and Chemicals Company.

Thermoplastic polyesters useful in the present invention include, butare not limited to, DESMOPHEN 2000 and DESMOPHEN 2001 KS, both of whichare commercially available from Bayer Corp. of Pittsburgh, Pa. Suitablepolyesters include, but are not limited to, RD-847A polyester resin,which is commercially available from Borden Chemicals of Columbus, Ohio,and DYNAKOLL Si 100 chemically modified rosin, which is commerciallyavailable from Eka Chemicals AB, Sweden. Useful polyamides include, butare not limited to, the VERSAMID products that are commerciallyavailable from Cognis Corp. of Cincinnati, Ohio, and EUREDOR productsthat are available from Ciba Geigy, Belgium. Useful thermoplasticpolyurethanes include, but are not limited to, WITCOBOND® W-290H, whichis commercially available from Crompton Corporation of Greenwich, Conn.,and RUCOTHANE® 2011L polyurethane latex, which is commercially availablefrom Ruco Polymer Corp. of Hicksville, N.Y.

The coating compositions of the present invention can comprise a mixtureof one or more thermosetting polymeric materials with one or morethermoplastic polymeric materials. In one embodiment of the presentinvention particularly useful for laminates for printed circuit boards,the polymeric materials of the aqueous sizing composition comprise amixture of RD-847A polyester resin, PVP K-30 polyvinyl pyrrolidone,DESMOPHEN 2000 polyester and VERSAMID polyamide. In an alternativeembodiment suitable for laminates for printed circuit boards, thepolymeric materials of the aqueous sizing composition comprise PVP K-30polyvinyl pyrrolidone, optionally combined with EPON 826 epoxy resin.

Semisynthetic polymeric materials suitable for use as polymericfilm-forming materials include, but are not limited to, cellulosics suchas hydroxypropylcellulose and modified starches such as KOLLOTEX 1250 (alow viscosity, low amylose potato-based starch etherified with ethyleneoxide) which is commercially available from AVEBE of The Netherlands.

Natural polymeric materials suitable for use as polymeric film-formingmaterials include, but are not limited to, starches prepared frompotatoes, corn, wheat, waxy maize, sago, rice, milo, and mixtures of anyof the foregoing.

It should be appreciated that depending on the nature of the starch, thestarch can function as both a particle 18 and/or a film-formingmaterial. More specifically, some starches will dissolve completely in asolvent, and in particular water, and function as a film formingmaterial while others will not completely dissolve and will maintain aparticular grain size and function as a particle 18. Although starches(both natural and semisynthetic) can be used in accordance with thepresent invention, the coating composition of the present invention canbe substantially free of starch materials. As used herein, the term“substantially free of starch materials” means that the coatingcomposition comprises less than 50 weight percent on a total solidsbasis of the coating composition, such as less than 35 weight of starchmaterials. In one embodiment, the coating composition of the presentinvention can be essentially free of starch materials. As used herein,the term “essentially free of starch materials” means that the coatingcomposition comprises less than 20 weight percent on a total solidsbasis of the coating composition, such as, for example, less than 5weight percent, and can be free of starch materials.

Typical primary sizing compositions containing starches that can beapplied to fiber strands to be incorporated into laminates for printedcircuit boards are not resin compatible and must be removed prior toincorporation into the polymeric matrix material. As previouslydiscussed, the coating compositions of the present invention are resincompatible and do not require removal from the fiber strands or fibersprior to fabric processing. In one embodiment, the coating compositionsof the present invention are compatible with matrix materials used tomake printed circuit boards (discussed below) and can be, for example,epoxy resin compatible.

The polymeric film-forming materials can be water soluble, emulsifiable,dispersible and/or curable. As used herein, “water soluble” means thatthe polymeric materials are capable of being essentially uniformlyblended and/or molecularly or ionically dispersed in water to form atrue solution. See Hawley's at page 1075, which is specificallyincorporated by reference herein. “Emulsifiable” means that thepolymeric materials are capable of forming an essentially stable mixtureor being suspended in water in the presence of an emulsifying agent. SeeHawley's at page 461, which is specifically incorporated by referenceherein. Nonlimiting examples of suitable emulsifying agents are setforth below. “Dispersible” means that any of the components of thepolymeric materials are capable of being distributed throughout water asfinely divided particles, such as a latex. See Hawley's at page 435,which is specifically incorporated by reference herein. The uniformityof the dispersion can be increased by the addition of wetting,dispersing or emulsifying agents (surfactants), which are discussedbelow. “Curable” means that the polymeric materials and other componentsof the sizing composition are capable of being coalesced into a film orcrosslinked to each other to change the physical properties of thepolymeric materials. See Hawley's at page 331, which is specificallyincorporated by reference herein.

In addition to or in lieu of the film forming materials discussed above,the coating compositions of the present invention can comprise one ormore glass fiber coupling agents such as organo-silane coupling agents,transition metal coupling agents, phosphonate coupling agents, aluminumcoupling agents, amino-containing Werner coupling agents, and mixturesof any of the foregoing. These coupling agents typically have dualfunctionality. Each metal or silicon atom has attached to it one or moregroups which can either react with or compatibilize the fiber surfaceand/or the components of the resin matrix. As used herein, the term“compatibilize” means that the groups are chemically attracted, but notbonded, to the fiber surface and/or the components of the coatingcomposition, for example by polar, wetting or solvation forces. In oneembodiment, each metal or silicon atom has attached to it one or morehydrolyzable groups that allow the coupling agent to react with theglass fiber surface, and one or more functional groups that allow thecoupling agent to react with components of the resin matrix. Examples ofhydrolyzable groups include, but are not limited to:

and the monohydroxy and/or cyclic C₂-C₃ residue of a 1,2- or 1,3 glycol,wherein R¹ is C₁-C₃ alkyl; R² is H or C₁-C₄ alkyl; R³ and R⁴ areindependently selected from H, C₁-C₄ alkyl or C₆-C₈ aryl; and R⁵ isC₄-C₇ alkylene. Examples of suitable compatibilizing or functionalgroups include, but are not limited to, epoxy, glycidoxy, mercapto,cyano, allyl, alkyl, urethano, carbamate, halo, isocyanato, ureido,imidazolinyl, vinyl, acrylato, methacrylato, amino or polyamino groups.

Functional organo-silane coupling agents can be used in the presentinvention. Examples of useful functional organo silane coupling agentsinclude, but are not limited to, gamma-aminopropyltrialkoxysilanes,gamma-isocyanatopropyltriethoxysilane, vinyl-trialkoxysilanes,glycidoxypropyltrialkoxysilanes and ureidopropyltrialkoxysilanes.Suitable functional organo-silane coupling agents include, but are notlimited to, A-187 gamma-glycidoxy-propyltrimethoxysilane, A-174gamma-methacryloxypropyltrimethoxysilane, A-1100gamma-aminopropyltriethoxysilane silane coupling agents, A-1108 aminosilane coupling agent and A-1160 gamma-ureidopropyltriethoxysilane (eachof which is commercially available from Crompton Corporation ofGreenwich, Conn.). The organo silane coupling agent can be at leastpartially hydrolyzed with water prior to application to the fibers, forexample, at a 1:1 stoichiometric ratio or, if desired, applied inunhydrolyzed form. The pH of the water can be modified by the additionof an acid or a base to initiate or speed the hydrolysis of the couplingagent as is well known in the art.

Suitable transition metal coupling agents include, but are not limitedto, titanium, zirconium, yttrium and chromium coupling agents. Suitabletitanate coupling agents and zirconate coupling agents are commerciallyavailable from Kenrich Petrochemical Company. Suitable chromiumcomplexes are commercially available from E.I. DuPont de Nemours ofWilmington, Del. The amino-containing Werner-type coupling agents arecomplex compounds in which a trivalent nuclear atom such as chromium iscoordinated with an organic acid having amino functionality. Other metalchelate and coordinate type coupling agents known to those skilled inthe art can be used herein.

The amount of coupling agent generally ranges from 1 to 99 weightpercent of the coating composition on a total solids basis. In oneembodiment, the amount of coupling agent can range from 1 to 30 weightpercent of the coating composition on a total solids basis, such as, forexample, from 1 to 10 weight percent, and from 2 to 8 weight percent.

The coating compositions of the present invention can further compriseone or more softening agents or surfactants that impart a uniform chargeto the surface of the fibers causing the fibers to repel from each otherand reducing the friction between the fibers, so as to function as alubricant. Although not required, the softening agents can be chemicallydifferent from other components of the coating composition. Suchsoftening agents include, but are not limited to, cationic, non-ionic oranionic softening agents and mixtures thereof, such as amine salts offatty acids, alkyl imidazoline derivatives such as CATION X, which iscommercially available from Rhone Poulenc/Rhodia of Princeton, N.J.,acid solubilized fatty acid amides, condensates of a fatty acid andpolyethylene imine and amide substituted polyethylene imines, such asEMERY® 6717, a partially amidated polyethylene imine commerciallyavailable from Cognis Corporation of Cincinnati, Ohio. While the coatingcomposition can comprise up to 60 weight percent of softening agents,the coating composition can comprise less than 20 weight percent such asless than 5 weight percent of the softening agents. For more informationon softening agents, see A. J. Hall, Textile Finishing, 2nd Ed. (1957)at pages 108-115, which are specifically incorporated by referenceherein.

The coating compositions of the present invention can further includeone or more lubricious materials that are chemically different from thepolymeric materials and softening agents discussed above to impartdesirable processing characteristics to the fiber strands duringweaving. Suitable lubricious materials can be selected from oils, waxes,greases, and mixtures of any of the foregoing. Nonlimiting examples ofwax materials useful in the present invention include aqueous soluble,emulsifiable or dispersible wax materials such as vegetable, animal,mineral, synthetic or petroleum waxes, e.g. paraffin. Oils useful in thepresent invention include, but are not limited to, both natural oils,semisynthetic oils and synthetic oils. Generally, the amount of wax orother lubricious material can range from 0 to 80 weight percent of thesizing composition on a total solids basis, such as, for example, from 1to 50 weight percent, from 20 to 40 weight percent, and from 25 to 35weight percent.

Suitable lubricious materials include, but are not limited to, waxes andoils having polar characteristics, and can include highly crystallinewaxes having polar characteristics and melting points above 35° C. suchas above 45° C. Such materials are believed to improve the wet-out andwet-through of polar resins on fiber strands coated with sizingcompositions containing such polar materials as compared to fiberstrands coated with sizing compositions containing waxes and oils thatdo not have polar characteristics. Suitable lubricious materials havingpolar characteristics can include, but are not limited to, esters formedfrom reacting (1) a monocarboxlyic acid and (2) a monohydric alcohol.Nonlimiting examples of such fatty acid esters useful in the presentinvention include cetyl palmitate (such as is available from StepanCompany of Maywood, N.J. as KESSCO 653 or STEPANTEX 653), cetylmyristate (also available from Stepan Company as STEPANLUBE 654), cetyllaurate, octadecyl laurate, octadecyl myristate, octadecyl palmitate andoctadecyl stearate. Other fatty acid ester, lubricious materials usefulin the present invention include, but are not limited to,trimethylolpropane tripelargonate, natural spermaceti and triglycerideoils, such as but not limited to soybean oil, linseed oil, epoxidizedsoybean oil, and epoxidized linseed oil.

The lubricious materials can also include water-soluble polymericmaterials. Nonlimiting examples of useful materials include polyalkylenepolyols and polyoxyalkylene polyols, such as MACOL E-300 which iscommercially available from BASF Corporation of Parsippany, N.J., andCARBOWAX 300 and CARBOWAX 400 which is commercially available from UnionCarbide Corporation, Danbury, Conn. Another nonlimiting example of auseful lubricious material is POLYOX WSR 301 which is a poly(ethyleneoxide) commercially available from Union Carbide Corporation, Danbury,Conn.

The coating compositions of the present invention can additionallyinclude one or more other lubricious materials, such as non-polarpetroleum waxes, in lieu of or in addition to of those lubriciousmaterials discussed above. Nonlimiting examples of non-polar petroleumwaxes include MICHEM® LUBE 296 microcrystalline wax, POLYMEKON® SPP-Wmicrocrystalline wax and PETROLITE 75 microcrystalline wax which arecommercially available from Michelman Inc. of Cincinnati, Ohio and BakerPetrolite, Polymer Division, of Cumming, Ga., respectively. Generally,the amount of this type of wax can be up to 10 weight percent of thetotal solids of the sizing composition.

The coating compositions of the present invention can also include aresin reactive diluent to further improve lubrication of the coatedfiber strands of the present invention and provide good processabilityin weaving and knitting by reducing the potential for fuzz, halos andbroken filaments during such manufacturing operations, while maintainingresin compatibility. As used herein, “resin reactive diluent” means thatthe diluent includes functional groups that are capable of chemicallyreacting with the same resin with which the coating composition iscompatible. The diluent can be any lubricant with one or more functionalgroups that react with a resin system, including functional groups thatreact with an epoxy resin system, such as, for example, functionalgroups that react with an FR-4 epoxy resin system. Nonlimiting examplesof suitable lubricants include lubricants with amine groups, alcoholgroups, anhydride groups, acid groups or epoxy groups. A nonlimitingexample of a lubricant with an amine group is a modified polyethyleneamine, e.g. EMERY 6717, which is a partially amidated polyethylene iminecommercially available from Cognis Corporation of Cincinnati, Ohio. Anonlimiting example of a lubricant with an alcohol group is polyethyleneglycol, e.g. CARBOWAX 300, which is a polyethylene glycol that iscommercially available from Union Carbide Corp. of Danbury, Conn. Anonlimiting example of a lubricant with an acid group is fatty acids,e.g. stearic acid and salts of stearic acids. Nonlimiting examples oflubricants with an epoxy group include epoxidized soybean oil andepoxidized linseed oil, e.g. FLEXOL LOE, which is an epoxidized linseedoil, and FLEXOL EPO, which is an epoxidized soybean oil, bothcommercially available from Union Carbide Corp. of Danbury, Conn., andLE-9300 epoxidized silicone emulsion, which is commercially availablefrom Crompton Corporation of Greenwich, Conn. Although not limiting inthe present invention, the sizing composition can include a resinreactive diluent as discussed above in an amount up to 15 weight percentof the sizing composition on a total solids basis.

In another embodiment, the coating compositions of the present inventioncan comprise at least one anionic, nonionic or cationic surface activeagent. As used herein, “surface active agent” means any material whichtends to lower the solid surface tension or surface energy of the curedcomposition or coating. For purposes of the present invention, solidsurface tension can be measured according to the Owens-Wendt methodusing a Rame'-Hart Contact Angle Goniometer with distilled water andmethylene iodide as reagents.

The at least one surface active agent can be selected from amphiphilic,reactive functional group-containing polysiloxanes, amphiphilicfluoropolymers, polyacrylates and mixtures of any of the foregoing. Withreference to water-soluble or water-dispersible amphiphilic materials,the term “amphiphilic” means a polymer having a generally hydrophilicpolar end and a water-insoluble generally hydrophobic end. Nonlimitingexamples of suitable amphiphilic fluoropolymers includefluoroethylene-alkyl vinyl ether alternating copolymers (such as thosedescribed in U.S. Pat. No. 4,345,057) available from Asahi Glass Companyunder the tradename LUMIFLON; fluorosurfactants, fluoroaliphaticpolymeric esters commercially available from 3M of St. Paul, Minn. underthe tradename FLUORAD; functionalized perfluorinated materials, such as1H, 1H-perfluoro-nonanol commercially available from FluoroChem USA; andperfluorinated (meth)acrylate resins. Other nonlimiting examples ofsuitable anionic surface active agents include sulfates or sulfonates.

Nonlimiting examples of suitable nonionic surface active agents includethose containing ether linkages and which are represented by thefollowing general formula: RO(R′O)_(n)H; wherein the substituent group Rrepresents a hydrocarbon group containing 6 to 60 carbon atoms, thesubstituent group R′ represents an alkylene group containing 2 or 3carbon atoms, and mixtures of any of the foregoing, and n is an integerranging from 2 to 100, inclusive of the recited values such as SURFYNOLnonionic polyoxyethylene surface active agents from Air ProductsChemicals, Inc.; PLURONIC or TETRONIC from BASF Corporation; TERGITOLfrom Union Carbide; and SURFONIC from Huntsman Corporation. Otherexamples of suitable nonionic surface active agents include, but are notlimited to, block copolymers of ethylene oxide and propylene oxide basedon a glycol such as ethylene glycol or propylene glycol including thoseavailable from BASF Corporation under the general trade designationPLURONIC.

Nonlimiting examples of suitable cationic surface active agents includeacid salts of alkyl amines; imidazoline derivatives; ethoxylated aminesor amides, a cocoamine ethoxylate; ethoxylated fatty amines; andglyceryl esters.

Other examples of suitable surface active agents include, but are notlimited to, homopolymers and copolymers of acrylate monomers, forexample polybutylacrylate and copolymers derived from acrylate monomers(such as ethyl (meth)acrylate, 2-ethylhexylacrylate, butyl(meth)acrylate and isobutyl acrylate), and hydroxy ethyl(meth)acrylateand (meth)acrylic acid monomers.

The amount of surface active agent can range from 1 to 50 weight percentof the coating composition on a total solids basis.

The coating compositions can additionally comprise one or moreemulsifying agents for emulsifying or dispersing components of thecoating compositions, such as the particles 18 and/or lubriciousmaterials. Nonlimiting examples of suitable emulsifying agents orsurfactants include polyoxyalkylene block copolymers (such as PLURONIC™F-108 polyoxypropylene-polyoxyethylene copolymer which is commerciallyavailable from BASF Corporation of Parsippany, N.J., (PLURONIC F-108copolymer is available in Europe under the tradename SYNPERONIC F-108),ethoxylated alkyl phenols (such as IGEPAL CA-630 ethoxylatedoctylphenoxyethanol which is commercially available from GAF Corporationof Wayne, N.J.), polyoxyethylene octylphenyl glycol ethers, ethyleneoxide derivatives of sorbitol esters (such as TMAZ 81 which iscommercially available BASF of Parsippany, N.J.), polyoxyethylatedvegetable oils (such as ALKAMULS EL-719, which is commercially availablefrom Rhone-Poulenc/Rhodia), ethoxylated alkylphenols (such as MACOLOP-10 SP which is also commercially available from BASF) and nonylphenolsurfactants (such as MACOL NP-6 and ICONOL NP-6 which are alsocommercially available from BASF, and SERMUL EN 668 which iscommercially available from CON BEA, Benelux). Generally, the amount ofemulsifying agent can range from 1 to 30 weight percent of the coatingcomposition on a total solids basis, such as from 1 to 15 weightpercent.

Crosslinking materials, such as melamine formaldehyde, and plasticizers,such as phthalates, trimellitates and adipates, can also be included inthe coating compositions. The amount of crosslinker or plasticizer canrange from 1 to 5 weight percent of the coating composition on a totalsolids basis.

Other additives can be included in the coating compositions, such assilicones, fungicides, bactericides and anti-foaming materials,generally in an amount of less than 5 weight percent. Organic and/orinorganic acids or bases in an amount sufficient to provide the coatingcomposition with a pH of 2 to 10 can also be included in the coatingcomposition. A nonlimiting example of a suitable silicone emulsion isLE-9300 epoxidized silicone emulsion, which is commercially availablefrom Crompton Corporation of Greenwich, Conn. An example of a suitablebactericide is BIOMET 66 antimicrobial compound, which is commerciallyavailable from M & T Chemicals of Rahway, N.J. Suitable anti-foamingmaterials are the SAG materials, which are commercially available fromCrompton Corporation of Greenwich, Conn. and MAZU DF-136, which isavailable from BASF Company of Parsippany, N.J. Ammonium hydroxide canbe added to the coating composition for coating stabilization, ifdesired. Water such as deionized water, can be included in the coatingcomposition in an amount sufficient to facilitate application of agenerally uniform coating upon the strand. The weight percentage ofsolids of the coating composition generally ranges from 1 to 20 weightpercent.

In one embodiment, the coating compositions of the present invention canbe substantially free of glass materials. As used herein, “substantiallyfree of glass materials” means that the coating compositions compriseless than 50 volume percent of glass matrix materials for forming glasscomposites, such as less than 35 volume percent. In another embodiment,the coating compositions of the present invention can be essentiallyfree of glass materials. As used herein, “essentially free of glassmaterials” means that the coating compositions comprise less than 20volume percent of glass matrix materials for forming glass composites,such as less than 5 volume percent, and can be free of glass materials.Examples of such glass matrix materials include, but are not limited to,black glass ceramic matrix materials or aluminosilicate matrix materialssuch as are well known to those skilled in the art.

In one embodiment of the present invention, a fiber strand comprising aplurality of fibers can be at least partially coated with a coatingcomprising an organic component and lamellar particles having a thermalconductivity of at least 1 Watt per meter K at a temperature of 300K. Inanother embodiment, a fiber strand comprising a plurality of fibers canbe at least partially coated with a coating comprising an organiccomponent and non-hydratable, lamellar particles. In each of theseembodiments, the organic component and the lamellar particles can beselected from the coating components discussed above. The organiccomponent and the lamellar particles can be the same or different, andthe coating can be a residue of an aqueous coating composition or apowdered coating composition.

In yet another embodiment, a fiber strand comprising a plurality offibers can be at least partially coated with a coating comprising atleast one boron-free lamellar particle having a thermal conductivity ofat least 1 Watt per meter K at a temperature of 300K. In anotherembodiment, a fiber strand comprising a plurality of fibers can be atleast partially coated with a residue of an aqueous compositioncomprising lamellar particles having a thermal conductivity of at least1 Watt per meter K at a temperature of 300K. In still anotherembodiment, a fiber strand comprising a plurality of fibers can be atleast partially coated with a residue of an aqueous compositioncomprising alumina-free, non-hydratable particles having a thermalconductivity of at least 1 Watt per meter K at a temperature of 300K.

The components in these embodiments can be selected from the coatingcomponents discussed above, and additional components can also beselected from those recited above.

In another embodiment of the present invention, a fiber strandcomprising a plurality of fibers can be at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising: (a) a plurality of discrete particles formed from materialsselected from non-heat expandable organic materials, inorganic polymericmaterials, non-heat expandable composite materials and mixtures thereof,the particles having an average particle size sufficient to allow strandwet out; (b) at least one lubricious material different from saidplurality of discrete particles; and (c) at least one film-formingmaterial. The components in these embodiments can be selected from thecoating components discussed above. In a further embodiment, theplurality of discrete particles provide an interstitial space betweenthe at least one of said fibers and at least one adjacent fiber.

In another embodiment, a fiber strand comprising a plurality of fiberscan be at least partially coated with a resin compatible coatingcomposition on at least a portion of a surface of at least one of saidfibers, the resin compatible coating composition comprising: (a) aplurality of particles comprising (i) at least one particle formed froman organic material; and (ii) at least one particle formed from aninorganic material selected from boron nitride, graphite and metaldichalcogenides, wherein the plurality of particles have an averageparticle size sufficient to allow strand wet out; (b) at least onelubricious material different from said plurality of discrete particles;and (c) at least one film-forming material.

In yet another embodiment, a fiber strand comprising a plurality offibers can be at least partially coated with a resin compatible coatingcomposition on at least a portion of a surface of at least one of saidfibers, the resin compatible coating composition comprising: (a) aplurality of discrete particles formed from materials selected fromorganic materials, inorganic polymeric materials, composite materialsand mixtures thereof, the particles having an average particle size,measured according to laser scattering techniques, ranging from 0.1 to 5micrometers; (b) at least one lubricious material different from saidplurality of discrete particles; and (c) at least one film-formingmaterial.

In a further embodiment, the resin compatible coating compositions setforth above can contain (a) 20 to 60 weight percent of the plurality ofdiscrete particles on total solids basis, such as, for example, from 35to 55 weight percent, and from 30 to 50 weight percent, (b) 0 to 80weight percent of the at least one lubricious material on a total solidsbasis, such as, for example, from 1 to 50 weight percent, and from 20 to40 weight percent, and (c) 1 to 60 weight percent of the at least onefilm-forming material on total solids basis, such as, for example, from5 to 50 weight percent, and from 10 to 30 weight percent.

In another embodiment of the present invention, a fiber strandcomprising a plurality of fibers can be at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising: (a) a plurality of discrete, non-waxy particles formed frommaterials selected from organic materials, composite materials andmixtures thereof, the particles having an average particle size,measured according to laser scattering techniques, ranging from 0.1 to 5micrometers; and (b) at least one lubricious material different fromsaid plurality of discrete particles.

In still another embodiment of the present invention, a fiber strandcomprising a plurality of fibers can be at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising greater than 20 weight percent on a total solids basis of atleast one particle selected from inorganic particles, organic hollowparticles and composite particles, the at least one particle having aMohs' hardness value which does not exceed the Mohs' hardness value ofat least one of said fibers.

In another embodiment of the present invention, a fiber strandcomprising a plurality of fibers can be at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising (a) at least one lamellar, inorganic particles having a Mohs'hardness value which does not exceed the Mohs' hardness value of atleast one of said fibers; and (b) at least one polymeric material.

In an additional embodiment of the present invention, a fiber strandcomprising a plurality of fibers can be at least partially coated with aresin compatible coating composition on at least a portion of a surfaceof at least one of said fibers, the resin compatible coating compositioncomprising (a) at least one hollow, non-heat expandable organicparticle; and (b) at least one lubricious material different from the atleast one hollow organic particle.

The components in each of the foregoing embodiments can be selected fromthe coating components discussed above, and additional components canalso be selected from those recited above.

In one embodiment of the present invention, a fiber can be coated with acomposition comprising an organic component and lamellar particleshaving a thermal conductivity of at least 1 Watt per meter K at atemperature of 300K. In another embodiment, a fiber can be coated with acomposition comprising an organic component and non-hydratable, lamellarparticles. In yet another embodiment, a fiber can be coated with acomposition comprising at least one boron-free lamellar particle havinga thermal conductivity greater than 1 Watt per meter K at a temperatureof 300K. In still another embodiment, a fiber can be coated with acomposition comprising at least one lamellar particle having a thermalconductivity greater than 1 Watt per meter K at a temperature of 300K.In yet another embodiment, a fiber can be coated with a compositioncomprising at least one alumina-free, non-hydratable inorganic particlehaving a thermal conductivity greater than 1 Watt per meter K at atemperature of 300K.

In another embodiment of the present invention, a fiber can be coatedwith a composition comprising (a) a plurality of discrete particlesformed from materials selected from non-heat expandable organicmaterials, inorganic polymeric materials, non-heat expandable compositematerials and mixtures thereof, the particles having an average particlesize sufficient to allow strand wet out, (b) at least one lubriciousmaterial different from said plurality of discrete particles, and (c) atleast one film-forming material. In yet another embodiment, a fiber canbe coated with a composition comprising (a) a plurality of particlescomprising (i) at least one particle formed from an organic material,and (ii) at least one particle formed from an inorganic materialselected from boron nitride, graphite and metal dichalcogenides, whereinthe plurality of particles have an average particle size sufficient toallow strand wet out, (b) at least one lubricious material differentfrom said plurality of discrete particles, and (c) at least onefilm-forming material.

In still another embodiment, a fiber can be coated with a compositioncomprising (a) a plurality of discrete particles formed from materialsselected from organic materials, inorganic polymeric materials,composite materials and mixtures thereof, the particles having anaverage particle size, measured according to laser scatteringtechniques, ranging from 0.1 to 5 micrometers, (b) at least onelubricious material different from said plurality of discrete particles,and (c) at least one film-forming material.

In another embodiment of the present invention, a fiber can be coatedwith a composition comprising (a) a plurality of discrete, non-waxyparticles formed from materials selected from organic materials,composite materials and mixtures thereof, the particles having anaverage particle size, measured according to laser scatteringtechniques, ranging from 0.1 to 5 micrometers, and (b) at least onelubricious material different from said plurality of discrete particles.In yet another embodiment, a fiber can be coated with a compositioncomprising a resin compatible coating composition comprising at leastone coating comprising greater than 20 weight percent on a total solidsbasis of a plurality of particles selected from inorganic particles,organic hollow particles and composite particles, said particles havinga Mohs' hardness value which does not exceed the Mohs' hardness value ofsaid glass fiber.

In another embodiment of the present invention, a fiber can be coatedwith a composition comprising (a) a plurality of lamellar, inorganicparticles, and (b) at least one polymeric material. In still anotherembodiment, a fiber can be coated with a composition comprising (a) aplurality of hollow, non-heat expandable organic particles, and (b) atleast one polymeric material different from the at least one holloworganic particle. In an additional embodiment, the present invention, afiber can be coated with a resin compatible coating composition having aprimary coating of a sizing composition on at least a portion of asurface of said fibers and a secondary coating comprising a residue ofan aqueous coating composition comprising a plurality of discreteparticles applied over at least a portion of the primary coating of thesizing composition.

The components in each of the foregoing embodiments can be selected fromthe coating components discussed above, and additional components canalso be selected from those recited above.

In one embodiment of the present invention, at least a portion of atleast one of said fibers of the fiber strand of the present inventioncan have applied thereto an aqueous coating composition comprisingPOLARTHERM® 160 boron nitride powder and/or BORON NITRIDE RELEASECOATdispersion, EPON 826 epoxy film-forming material, PVP K-30 polyvinylpyrrolidone, A-187 epoxy-functional organo silane coupling agent,ALKAMULS EL-719 polyoxyethylated vegetable oil, IGEPAL CA-630ethoxylated octylphenoxyethanol, KESSCO PEG 600 polyethylene glycolmonolaurate ester which is commercially available from Stepan Company ofChicago, Ill. and EMERY® 6717 partially amidated polyethylene imine.

In another embodiment of the present invention for weaving cloth, atleast a portion of at least one of said glass fibers of the fiber strandof the present invention can have applied thereto a dried residue of anaqueous sizing composition comprising POLARTHERM® 160 boron nitridepowder and/or BORON NITRIDE RELEASECOAT dispersion, RD-847A polyester,PVP K-30 polyvinyl pyrrolidone, DESMOPHEN 2000 polyester, A-174acrylic-functional organo silane coupling agents and A-187epoxy-functional organo silane coupling agents, PLURONIC F-108polyoxypropylene-polyoxyethylene copolymer, MACOL NP-6 nonylphenolsurfactant, VERSAMID 140 and LE-9300 epoxidized silicone emulsion.

In another embodiment of a fabric for use in electronic circuit boardsof the present invention, at least a portion of at least one of saidglass fibers of the fiber strand of the present invention can haveapplied thereto an aqueous coating composition comprising POLARTHERM® PT160 boron nitride powder and/or ORPAC BORON NITRIDE RELEASECOAT-CONC 25dispersion, PVP K-30 polyvinyl pyrrolidone, A-174 acrylic-functionalorgano silane coupling agent, A-187 epoxy-functional organo silanecoupling agent, ALKAMULS EL-719 polyoxyethylated vegetable oil, EMERY®6717 partially amidated polyethylene imine, RD-847A polyester, DESMOPHEN2000 polyester, PLURONIC F-108 polyoxypropylene-polyoxyethylenecopolymer, ICONOL NP-6 alkoxylated nonyl phenol and SAG 10 anti-foamingmaterial. If desired, this particular embodiment can optional furthercomprise ROPAQUE® HP-1055 and/or ROPAQUE® OP-96 styrene-acryliccopolymer hollow spheres.

In another embodiment of fabric for use in electronic circuit boards ofthe present invention, at least a portion of at least one of said glassfibers of the fiber strand of the present invention can have appliedthereto a residue of an aqueous sizing composition comprisingPOLARTHERM® PT 160 boron nitride powder and/or ORPAC BORON NITRIDERELEASECOAT-CONC 25 dispersion, RD-847A polyester, PVP K-30 polyvinylpyrrolidone, DESMOPHEN 2000 polyester, A-174 acrylic-functional organosilane coupling agent, A-187 epoxy-functional organo silane couplingagent, PLURONIC F-108 polyoxypropylene-polyoxyethylene copolymer,VERSAMID 140 polyamide, and MACOL NP-6 nonyl phenol. If desired, thisparticular embodiment can optional further comprise ROPAQUE® HP-1055and/or ROPAQUE® OP-96 styrene-acrylic copolymer hollow spheres.

In still another embodiment for weaving fabric for use in laminatedprinted circuit boards, at least a portion of at least one of said glassfibers of the fiber strand of the present invention can have appliedthereto a residue of an aqueous primary coating composition comprisingROPAQUE® HP-1055 and/or ROPAQUE® OP-96 styrene-acrylic copolymer hollowspheres, PVP K-30 polyvinyl pyrrolidone, A-174 acrylic-functional organosilane coupling agents and A-187 epoxy-functional organo silane couplingagents, EMERY® 6717 partially amidated polyethylene imine, STEPANTEX 653cetyl palmitate, TMAZ 81 ethylene oxide derivatives of sorbitol esters,MACOL OP-10 ethoxylated alkylphenol and MAZU DF-136 anti-foamingmaterial. Although not required, this particular embodiment can furthercomprise POLARTHERM® PT 160 boron nitride powder and/or ORPAC BORONNITRIDE RELEASECOAT-CONC 25 dispersion, and FLEXOL EPO epoxidizedsoybean oil.

In yet another embodiment of fabric for use in electronic circuit boardsof the present invention, at least a portion of at least one of saidglass fibers of the fiber strand of the present invention can haveapplied thereto a residue of an aqueous coating composition comprisingDESMOPHEN 2000 polyester, A-174 acrylic-functional organo silanecoupling agent, A-187 epoxy-functional organo silane coupling agent,PLURONIC F-108 polyoxypropylene-polyoxyethylene copolymer, VERSAMID 140polyamide, MACOL NP-6 nonyl phenol, POLYOXWSR 301 poly(ethylene oxide)and DYNAKOLL Si 100 rosin. In addition, this particular embodimentfurther comprises ROPAQUE® HP-1055 and/or ROPAQUE® OP-96 styrene-acryliccopolymer hollow spheres, and/or POLARTHERM® PT 160 boron nitride powderand/or ORPAC BORON NITRIDE RELEASECOAT-CONC 25 dispersion.

In another embodiment of fabric for use in electronic circuit boards ofthe present invention, at least a portion of at least one of said glassfibers of the fiber strand of the present invention can have appliedthereto a residue of an aqueous coating composition comprising DESMOPHEN2000 polyester, A-174 acrylic-functional organo silane coupling agent,A-187 epoxy-functional organo silane coupling agent, SYNPERONIC F-108polyoxypropylene-polyoxyethylene copolymer, EUREDUR 140 polyamide, MACOLNP-6 nonyl phenol, SERMUL EN 668 ethoxylated nonylphenol, POLYOX WSR 301poly(ethylene oxide) and DYNAKOLL Si 100 rosin. In addition, thisparticular embodiment further comprises ROPAQUE® HP-1055 and/or ROPAQUE®OP-96 styrene-acrylic copolymer hollow spheres, and/or POLARTHERM® PT160 boron nitride powder and/or ORPAC BORON NITRIDE RELEASECOAT-CONC 25dispersion.

The fiber strands having a residue of a coating composition similar tothose described above that are free of particles 18 can be made inaccordance with the present invention. In particular, it is contemplatedthat resin compatible coating compositions comprising one or morefilm-forming materials, such as PVP K-30 polyvinyl pyrrolidone; one ormore silane coupling agents, such as A-174 acrylic-functional organosilane coupling agents and A-187 epoxy-functional organo silane couplingagents; and at least 25 percent by weight of the sizing composition on atotal solids basis of a lubricious material having polarcharacteristics, such as STEPANTEX 653 cetyl palmitate, can be made inaccordance with the present invention. It will be further appreciated bythose skilled in the art that fiber strands having a resin compatiblecoating composition that is essentially free of particles 18 can bewoven into fabrics and made into electronic supports and electroniccircuit boards (as described below) in accordance with the presentinvention.

The coating compositions of the present invention can be prepared by anysuitable method such as conventional mixing well known to those skilledin the art. In one embodiment, the components discussed above arediluted with water to have the desired weight percent solids and mixedtogether. The particles 18 can be premixed with water, emulsified orotherwise added to one or more components of the coating compositionprior to mixing with the remaining components of the coating.

Coating compositions according to the present invention can be appliedin many ways, for example by contacting the filaments with a roller orbelt applicator, spraying or other means. The coated fibers can be driedat room temperature or at elevated temperatures. The dryer removesexcess moisture from the fibers and, if present, cures any curablesizing composition components. The temperature and time for drying theglass fibers will depend upon such variables as the percentage of solidsin the coating composition, components of the coating composition andtype of fiber.

As used herein, the term “cure” as used in connection with acomposition, e.g., “a cured composition,” shall mean that anycrosslinkable components of the composition are at least partiallycrosslinked. In certain embodiments of the present invention, thecrosslink density of the crosslinkable components, i.e., the degree ofcrosslinking, ranges from 5% to 100% of complete crosslinking. In otherembodiments, the crosslink density can range from 35% to 85% of fullcrosslinking. In other embodiments, the crosslink density can range from50% to 85% of full crosslinking. One skilled in the art will understandthat the presence and degree of crosslinking, i.e., the crosslinkdensity, can be determined by a variety of methods, such as dynamicmechanical thermal analysis (DMTA) using a Polymer Laboratories MK IIIDMTA analyzer conducted under nitrogen. This method determines the glasstransition temperature and crosslink density of free films of coatingsor polymers. These physical properties of a cured material are relatedto the structure of the crosslinked network.

According to this method, the length, width, and thickness of a sampleto be analyzed are first measured, the sample is tightly mounted to thePolymer Laboratories MK III apparatus, and the dimensional measurementsare entered into the apparatus. A thermal scan is run at a heating rateof 3° C./min, a frequency of 1 Hz, a strain of 120%, and a static forceof 0.01N, and sample measurements occur every two seconds. The mode ofdeformation, glass transition temperature, and crosslink density of thesample can be determined according to this method. Higher crosslinkdensity valves indicate a higher degree of crosslinking in the coating.

The amount of the coating composition present on the fiber strand can beless than 30 percent by weight, such as, for example, less than 10percent by weight and from 0.1 to 5 percent by weight as measured byloss on ignition (LOI). The coating composition on the fiber strand canbe a residue of an aqueous coating composition or a powdered coatingcomposition. In one embodiment of the invention, the LOI can be lessthan 1 percent by weight. As used herein, the term “loss on ignition”means the weight percent of dried coating composition present on thesurface of the fiber strand as determined by Equation 1:

LOI=100×[(W _(dry) −W _(bare))/W _(dry)]  (Eq. 1)

wherein W_(dry) is the weight of the fiber strand plus the weight of thecoating composition after drying in an oven at 220° F. (about 104° C.)for 60 minutes and W_(bare) is the weight of the bare fiber strand afterheating the fiber strand in an oven at 1150° F. (about 621° C.) for 20minutes and cooling to room temperature in a dessicator.

After the application of a primary size, i.e., the initial size appliedafter fiber formation, the fibers are gathered into strands having 2 to15,000 fibers per strand, such as 100 to 1600 fibers per strand.

A secondary coating composition can be applied to the primary size in anamount effective to coat or impregnate the portion of the strands, forexample by dipping the coated strand in a bath containing the secondarycoating composition, spraying the secondary coating composition upon thecoated strand or by contacting the coated strand with an applicator asdiscussed above. The coated strand can be passed through a die to removeexcess coating composition from the strand and/or dried as discussedabove for a time sufficient to at least partially dry or cure thesecondary coating composition. The method and apparatus for applying thesecondary coating composition to the strand is determined in part by theconfiguration of the strand material. The strand can be dried afterapplication of the secondary coating composition in a manner well knownin the art.

Suitable secondary coating compositions can include one or morefilm-forming materials, lubricants and other additives such as arediscussed above. The secondary coating can be different from the primarysizing composition, i.e., it (1) contains at least one component whichis chemically different from the components of the sizing composition;or (2) contains at least one component in an amount which is differentfrom the amount of the same component contained in the sizingcomposition. Nonlimiting examples of suitable secondary coatingcompositions including polyurethane are disclosed in U.S. Pat. Nos.4,762,750 and 4,762,751, which are specifically incorporated byreference herein.

Referring now to FIG. 2, in an alternative embodiment according to thepresent invention, the glass fibers 212 of the coated fiber strand 210can have applied thereto a primary layer 214 of a primary sizingcomposition which can comprise any of the sizing components in theamounts discussed above. Examples of suitable sizing compositions areset forth in Loewenstein at pages 237-291 (3d Ed. 1993) and U.S. Pat.Nos. 4,390,647 and 4,795,678, each of which is specifically incorporatedby reference herein. A secondary layer 215 of a secondary coatingcomposition can be applied to at least a portion, and can be over theentire outer surface, of the primary layer 214. The secondary coatingcomposition comprises one or more types of particles 216 such as arediscussed in detail above as particles 18. In one embodiment, thesecondary coating can be a residue of an aqueous secondary coatingcomposition, and, in particular, a residue of an aqueous secondarycoating composition comprising lamellar particles on at least a portionof the primary coating. In another embodiment, the secondary coating canbe a powdered coating composition, and, in particular, a powderedcoating composition comprising lamellar particles on at least a portionof the primary coating.

In an alternative embodiment, the particles of the secondary coatingcomposition comprise hydrophilic inorganic solid particles that absorband retain water in the interstices of the hydrophilic particles. Thehydrophilic inorganic solid particles can absorb water or swell when incontact with water or participate in a chemical reaction with the waterto form, for example, a viscous gel-like solution which blocks orinhibits further ingress of water into the interstices of atelecommunications cable which the coated glass fiber strand is used toreinforce. As used herein, “absorb” means that the water penetrates theinner structure or interstices of the hydrophilic material and issubstantially retained therein. See Hawley's Condensed ChemicalDictionary at page 3, which is specifically incorporated by referenceherein. “Swell” means that the hydrophilic particles expand in size orvolume. See Webster's New Collegiate Dictionary (1977) at page 1178,which is specifically incorporated by reference herein. In oneembodiment, the hydrophilic particles swell after contact with water toat least one and one-half times their original dry weight, such as fromtwo to six times their original weight. Nonlimiting examples ofhydrophilic inorganic solid lubricant particles that swell includesmectites such as vermiculite and montmorillonite, absorbent zeolitesand inorganic absorbent gels. These hydrophilic particles can be appliedin powder form over tacky sizing or other tacky secondary coatingmaterials.

In one embodiment of the present invention, a fiber strand comprising aplurality of fibers can be at least partially coated with a resincompatible coating composition on at least a portion of a surface of theat least one fiber, the resin compatible coating composition having aprimary coating of a sizing composition on at least a portion of asurface of the at least one fiber, and a secondary coating comprising aresidue of an aqueous coating composition comprising at least onediscrete particle applied over at least a portion of the primary coatingof the sizing composition. In another embodiment, the at least onediscrete particle can be selected from a hydrophilic particle whichabsorbs and retains water in interstices of the hydrophilic particle.

Further to these embodiments, the amount of particles in the secondarycoating composition can range from 1 to 99 weight percent on a totalsolids basis, such as, for example, from 20 to 90, from 25 to 80 weightpercent, and from 50 to 60 weight percent.

In an alternative embodiment shown in FIG. 3, a tertiary layer 320 of atertiary coating composition can be applied to at least a portion of thesurface, such as over the entire surface, of a secondary layer 315,i.e., such a fiber strand 312 would have a primary layer 314 of aprimary sizing, a secondary layer 315 of a secondary coating compositionand a tertiary, outer layer 320 of the tertiary coating. The tertiarycoating of the coated fiber strand 310 can be different from the primarysizing composition and the secondary coating composition, i.e., thetertiary coating composition (1) contains at least one component whichis chemically different from the components of the primary sizing andsecondary coating composition; or (2) contains at least one component inan amount which is different from the amount of the same componentcontained in the primary sizing or secondary coating composition.

In this embodiment, the secondary coating composition comprises one ormore polymeric materials discussed above, such as polyurethane, and thetertiary powdered coating composition comprises solid particles, such asthe POLARTHERM® boron nitride particles, and hollow particles, such asROPAQUE® pigments, which are discussed above. In one embodiment, thepowdered coating can be applied by passing the strand having a liquidsecondary coating composition applied thereto through a fluidized bed orspray device to adhere the powder particles to the tacky secondarycoating composition. Alternatively, the strands can be assembled into afabric 912 before the layer of tertiary coating 920 is applied, as shownin FIG. 9. Composite or laminate 910, which combines fabric 912 with aresin 914, also comprises an electrically conductive layer 922, similarto the construction shown in FIG. 8 which will be discussed later ingreater detail. The weight percent of powdered solid particles adheredto the coated fiber strand 310 can range from 0.1 to 75 weight percentof the total weight of the dried strand, and such as from 0.1 to 30weight percent.

The tertiary powdered coating can also comprise one or more polymericmaterials such as are discussed above, such as acrylic polymers,epoxies, or polyolefins, conventional stabilizers and other modifiersknown in the art of such coatings, and can be in dry powder form.

In one embodiment, a fiber strand comprising a plurality of fibers canbe at least partially coated with a primary coating of a sizingcomposition applied to at least a portion of a surface of the at leastone fiber, a secondary coating composition comprising a polymericmaterial applied to at least a portion of the primary composition, and atertiary coating composition comprising discrete particles applied to atleast a portion of the secondary coating. In another embodiment, a fiberstrand comprising a plurality of fibers can be at least partially coatedwith a primary coating of a sizing composition applied to at least aportion of a surface of at least one of said fibers, a secondary coatingcomposition comprising a polymeric material applied to at least aportion of the primary composition, and a tertiary coating compositioncomprising lamellar particles applied to at least a portion of thesecondary coating.

In one embodiment, at least one of the coatings in each of the foregoingembodiments can be different. In another embodiment, at least two of thecoatings in each of the foregoing embodiments are the same.Additionally, the tertiary coating can be a residue of an aqueousemulsion or a powdered coating composition. The coating compositionscomprise one or more coating components discussed above.

The various embodiments of the coated fiber strands discussed above canbe used as continuous strand or further processed into diverse productssuch as chopped strand, twisted strand, roving and/or fabric, such aswovens, nonwovens (including, but not limited to, unidirectional,biaxial and triaxial fabrics), knits, mats (both chopped and continuousstrand mats) and multilayered fabrics (i.e. overlaying layers of fabricheld together by stitching or some other material to form athree-dimensional fabric structure). In addition, the coated fiberstrands used as warp and weft (i.e. fill) strands of a fabric can benon-twisted (also referred to as untwisted or zero twist) or twistedprior to weaving and the fabric can include, but is not limited to,various combinations of both twisted and non-twisted warp and weftstrands.

Certain embodiments of the present invention can comprise an at leastpartially coated fabric comprising at least one of the fiber strandscomprising a plurality of fibers discussed in detail above. Thus, an atleast partially coated fabric made from each of the disclosed fiberstrands comprising a plurality of fibers is, therefore, contemplated inthe present invention. For example, one embodiment of the presentinvention can be directed to an at least partially coated fabriccomprising at least one strand comprising plurality of fibers, thecoating comprising an organic component and lamellar particles having athermal conductivity of at least 1 Watt per meter K at a temperature of300K.

In one embodiment of the present invention, the coating compositionsaccording to the present invention can be applied to an individualfiber. In another embodiment, the coating can be applied to at least onefiber strand. In another embodiment, the coating composition accordingto the present invention is applied to the fabric. These alternativeembodiments are fully discussed below.

Although the prior discussion is generally directed toward applying thecoating composition of the present invention directly on glass fibersafter fiber forming and subsequently incorporating the fibers into afabric, the present invention also includes embodiments wherein thecoating composition of the present invention can be applied to a fabric.The coating composition can be applied to a fabric, for example, byapplying the coating to a fiber strand before the fabric ismanufactured, or by applying the coating to the fabric after it has beenmanufactured using various techniques well known in the art. Dependingon the processing of the fabric, the coating composition of the presentinvention can be applied either directly to the glass fibers in thefabric or to another coating already on the glass fibers and/or fabric.For example, the glass fibers can be coated with a conventionalstarch-oil sizing after forming and woven into a fabric. The fabric canthen be treated to remove starch-oil sizing prior to applying thecoating composition of the present invention. This sizing removal can beaccomplished using techniques well known in the art, such as thermaltreatment or washing of the fabric. In this instance, the coatingcomposition would directly coat the surface of the fibers of the fabric.If any portion of the sizing composition initially applied to the glassfibers after forming is not removed, the coating composition of thepresent invention would then be applied over the remaining portion ofthe sizing composition rather than directly to the fiber surface.

In another embodiment of the present invention, selected components ofthe coating composition of the present invention can be applied to theglass fibers immediately after forming and the remaining components ofthe coating composition can be applied to the fabric after it is made.In a manner similar to that discussed above, some or all of the selectedcomponents can be removed from the glass fibers prior to coating thefibers and fabric with the remaining components. As a result, theremaining components will either directly coat the surface of the fibersof the fabric or coat those selected components that were not removedfrom the fiber surface.

In another embodiment according to the present invention, a fabriccomprising at least one strand comprising a plurality of fibers can beat least partially coated with a primary coating and a secondary coatingon at least a portion of the primary coating, the secondary coatingcomprising particles of an inorganic material having a thermalconductivity greater than 1 Watts per meter K at a temperature of 300K.

In another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers can be at least partially coated withcoating comprising (a) lamellar, inorganic particles having a Mohs'hardness value which does not exceed the Mohs' hardness value of the atleast one glass fiber, and (b) a film-forming material.

In yet another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers can be at least partially coated with acoating comprising (a) metallic particles having a Mohs' hardness valuewhich does not exceed the Mohs' hardness value of the at least one glassfiber, the metallic particles being selected from indium, thallium, tin,copper, zinc, gold and silver, and (b) a film-forming material.

In another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers can be at least partially coated with aprimary coating and a secondary coating on at least a portion of theprimary coating, the secondary coating comprising a plurality ofhydrophilic particles which absorb and retain water in the intersticesof the hydrophilic particles.

In still another embodiment of the present invention, a fabriccomprising at least one strand comprising a plurality of fibers can havea resin compatible coating composition on at least a portion of asurface of the fabric, the resin compatible coating compositioncomprising (a) a plurality of discrete particles formed from materialsselected from organic materials, inorganic polymeric materials,composite materials and mixtures thereof, the particles having anaverage particle size, measured according to laser scattering, rangingfrom 0.1 to 5 micrometers, (b) at least one lubricious materialdifferent from said plurality of discrete particles, and (c) at leastone film-forming material.

In another embodiment, a fabric comprising at least one strandcomprising a plurality of fibers can have a resin compatible coatingcomposition on at least a portion of a surface of the fabric, the resincompatible coating composition comprising (a) a plurality of discrete,non-waxy particles formed from materials selected from organicmaterials, composite materials and mixtures thereof, and at least onelubricious material different from said plurality of discrete particles.

In another embodiment of the present invention, a fabric comprising atleast one strand comprising a plurality of fibers can have a resincompatible coating composition on at least a portion of a surface of thefabric, the resin compatible coating composition comprising (a) aplurality of hollow organic particles, and (b) at least one polymericmaterial different from the hollow organic particles.

Another embodiment of present invention can be directed to a fabriccomprising at least one strand comprising a plurality of fibers, whereinat least a portion of the fabric has a resin compatible coating with aloss on ignition of ranging from 0.1 to 1.6, and an air permeability,measured according to ASTM D 737, of no greater than 10 standard cubicfeet per minute per square foot. As used herein, “air permeability”means how permeable the fabric is to flow of air therethrough. Airpermeability can be measured by ASTM D 737 Standard Test Method for AirPermeability of Textile Fabrics, which is specifically incorporated byreference herein.

These components used in these various embodiments can be selected fromthe coating components discussed above, and additional components canalso be selected from those recited above.

In one embodiment of the present invention, a fabric adapted toreinforce an electronic support can be made by a method comprising:

(a) obtaining at least one fill yarn comprising a plurality of fibersand having a first resin compatible coating on at least a portion of theat least one fill yarn;

(b) obtaining at least one warp yarn comprising a plurality of fibersand having a second resin compatible coating on at least a portion ofthe at least one warp yarn; and

(c) weaving the at least one fill yarn and the at least one warp yarnhaving a loss on ignition of less than 2.5 percent by weight to form afabric adapted to reinforce an electronic support.

In an additional embodiment of the present invention, a fabric can beassembled by (a) slidingly contacting at least a portion of a firstglass fiber strand comprising a plurality of glass fibers having on atleast a portion of surfaces thereof a coating according to any of theprevious embodiments, either individually or in combination, whichinhibit abrasive wear of the surfaces of the plurality of glass fibers,in sliding contact with surface asperities of a portion of a fabricassembly device, the surface asperities having a Mohs' hardness valuewhich is greater than a Mohs' hardness value of glass fibers of thefirst glass fiber strand; and (b) interweaving the first glass fiberstrand with a second fiber strand to form a fabric.

Further embodiments of the present invention are directed to methods forinhibiting abrasive wear of a fiber strand comprising at least one glassfiber by sliding contact with surface asperities of a solid objectcomprising:

(a) applying a coating composition according to any of the previousembodiments, either individually or in combination, to at least aportion of a surface of at least one glass fiber of a glass fiberstrand;

(b) at least partially drying the composition to form a sized glassfiber strand having a residue of the composition upon at least a portionof the surface of the at least one glass fiber; and

(c) sliding at least a portion of the glass fiber strand to contactsurface asperities of a solid object, the surface asperities having ahardness value which is greater than a hardness value of the at leastone glass fiber, such that abrasive wear of the at least one glass fiberof the glass fiber strand by contact with the surface asperities of thesolid object is inhibited by the coating composition.

As above, the components of the coatings used in these embodiments canbe selected from the coating components discussed above, and additionalcomponents can also be selected from those recited above.

The coated fiber strands 10, 210, 310 and products formed therefrom,such as the coated fabrics recited above, can be used in a wide varietyof applications, such as, for example, reinforcements 410 forreinforcing polymeric matrix materials 412 to form a composite 414, suchas is shown in FIG. 4, which will be discussed in detail below. Suchapplications include, but are not limited to, laminates for printedcircuit boards, reinforcements for telecommunications cables, andvarious other composites.

The coated strands and fabrics of the present invention can becompatible with typical polymeric matrix resins used to make electronicsupports and printed circuit boards. In addition, the coated fiberstrands can be suitable for use on air-jet looms, which are commonlyused to make the reinforcing fabrics for such applications. Conventionalsizing compositions applied to fibers to be woven using air-jet loomscomprise components such as starches and oils that are generally notcompatible with such resin systems. It has been observed that weavingcharacteristics of fiber strands coated with a coating compositioncomprising particles 18 in accordance with the present inventionapproximate the weaving characteristics of fiber strands coated withconventional starch/oil based sizing compositions and are compatiblewith FR-4 epoxy resins. Although not meant to be bound by any particulartheory, it is believed that the particles 18 of the instant inventionfunction in a manner similar to the starch component of conventionalstarch/oil sizing compositions during processing and air-jet weaving byproviding the necessary fiber separation and air drag for the air jetweaving operation but function in a manner different from theconventional compositions by providing compatibility with the epoxyresin system. For example, the particles 18 contribute a dry, powdercharacteristic to the coating similar to the dry lubricantcharacteristics of a starch coating.

In the coated strands of the present invention, the particles canadvantageously provide interstices between the fibers of the strandwhich facilitate flow of the matrix materials therebetween to morequickly and/or uniformly wet-out and wet-through the fibers of thestrand. Additionally, the strands can have high strand openness(discussed above) which also facilitates flow of the matrix materialinto the bundles. Surprisingly, in certain embodiments, the amount ofparticles can exceed 20 weight percent of the total solids of thecoating composition applied to the fibers, yet still be adequatelyadhered to the fibers and provide strands having handlingcharacteristics at least comparable to strands without the particlecoating.

Referring now to FIG. 8, one advantage of the coated strands of thepresent invention is that laminates 810 made from fabrics 812incorporating the coated strands can have good coupling at the interfacebetween the fabric 812 and the polymeric matrix material 814. Goodinterfacial coupling can provide for good hydrolytic stability andresistance to metal migration (previously discussed) in electronicsupports 818 made from laminates 810.

In another embodiment shown in FIG. 5, coated fiber strands 510 madeaccording to the present invention can be used as warp and/or weftstrands 514, and 516 in a knit or woven fabric 512 reinforcement, andcan form a laminate for a printed circuit board (shown in FIGS. 7-9).Although not required, the warp strands 514 can be twisted prior to useby any conventional twisting technique known to those skilled in theart. One such technique uses twist frames to impart twist to the strandat 0.5 to 3 turns per inch. The reinforcing fabric 512 can comprise 5 to100 warp strands 514 per centimeter (about 13 to 254 warp strand perinch) and 6 to 50 weft strands per centimeter (about 15 to about 127weft strands per inch). The weave construction can be a regular plainweave or mesh (shown in FIG. 5), although any other weaving style wellknown to those skilled in the art, such as a twill weave or satin weave,can be used.

In one embodiment, a suitable woven reinforcing fabric 512 of thepresent invention can be formed by using any conventional loom wellknown to those skilled in the art, such as a shuttle loom, air jet loomor rapier loom. In another embodiment, suitable woven reinforcing fabric512 of the present invention can be formed using an air jet loom.Suitable air jet looms are commercially available from Tsudakoma ofJapan as Model Nos. 103,1031,1033 or ZAX; Sulzer Ruti Model Nos. L-5000,L-5100 or L-5200 which are commercially available from Sulzer BrothersLTD. of Zurich, Switzerland; and Toyoda Model No. JAT610.

As set forth in the figures, air jet weaving refers to a type of fabricweaving using an air jet loom 626 (shown in FIG. 6) in which the fillyarn (weft) 610 is inserted into the warp shed by a blast of compressedair 614 from one or more air jet nozzles 618 (shown in FIGS. 6 and 6a),as discussed above. The fill yarn 610 is propelled across the width 624of the fabric 628 (about 10 to about 60 inches), such as 0.91 meters(about 36 inches) by the compressed air.

The air jet filling system can have a single, main nozzle 616, but canalso have a plurality of supplementary, relay nozzles 620 along the warpshed 612 for providing blasts of supplementary air 622 to the fill yarn610 to maintain the desired air pressure as the yarn 610 traverses thewidth 624 of the fabric 628. The air pressure (gauge) supplied to themain air nozzle 616 can range from 103 to 413 kilopascals (kPa) (about15 to about 60 pounds per square inch (psi)), such as, for example, 310kPa (about 45 psi). A style of main air nozzle 616 is a Sulzer Rutineedle air jet nozzle unit Model No. 044 455 001 which has an internalair jet chamber having a diameter 617 of 2 millimeters and a nozzle exittube 619 having a length 621 of 20 centimeters (commercially availablefrom Sulzer Ruti of Spartanburg, N.C.). The air jet filling system canhave 15 to 20 supplementary air nozzles 620 which supply auxiliaryblasts of air in the direction of travel of the fill yarn 610 to assistin propelling the yarn 610 across the loom 626. The air pressure (gauge)supplied to each supplementary air nozzle 620 can range from 3 to 6bars.

The fill yarn 610 is drawn from the supply package 630 by a feedingsystem 632 at a feed rate of 180 to 550 meters per minute, such as 274meters (about 300 yards) per minute. The fill yarn 610 is fed into themain nozzle 618 through a clamp. A blast of air propels a predeterminedlength of yarn (approximately equal to the desired width of the fabric)through the confusor guide. When the insertion is completed, the end ofthe yarn distal to the main nozzle 618 is cut by a cutter 634.

The compatibility and aerodynamic properties of different yarns with theair jet weaving process can be determined by the following method, whichwill generally be referred to herein as the “Air Jet Transport DragForce” Test Method. The Air Jet Transport Drag Force Test can be used tomeasure the attractive or pulling force (“drag force”) exerted upon theyarn as the yarn is pulled into the air jet nozzle by the force of theair jet. In this method, each yarn sample is fed at a rate of 274 meters(about 300 yards) per minute through a Sulzer Ruti needle air jet nozzleunit Model No. 044 455 001 which has an internal air jet chamber havinga diameter 617 of 2 millimeters and a nozzle exit tube 619 having alength 621 of 20 centimeters (commercially available from Sulzer Ruti ofSpartanburg, N.C.) at an air pressure of 310 kiloPascals (about 45pounds per square inch) gauge. A tensiometer is positioned in contactwith the yarn at a position prior to the yarn entering the air jetnozzle. The tensiometer provides a measurement of the gram force (dragforce) exerted upon the yarn by the air jet as the yarn is pulled intothe air jet nozzle.

The drag force per unit mass can be used as a basis for relativecomparison of yarn samples. For relative comparison, the drag forcemeasurements are normalized over a one centimeter length of yarn. TheGram Mass of a one centimeter length of yarn can be determined accordingto Equation 2:

Gram Mass=(π(d/2)²)(N)(ρ_(glass))(1 centimeter length of yarn)  (Eq. 2)

where d is the diameter of a single fiber of the yarn bundle, N is thenumber of fibers in the yarn bundle and ρ_(glass) is the density of theglass at a temperature of 25° C. (about 2.6 grams per cubic centimeter).Table C lists the diameters and number of fibers in a yarn for severaltypical glass fiber yarn products.

TABLE C Fiber Diameter Yarn type (centimeters) Number of Fibers inBundle G75 9 × 10⁻⁴ 400 G150 9 × 10⁻⁴ 200 E225 7 × 10⁻⁴ 200 D450 5.72 ×10⁻⁴ 200

For example, the Gram Mass of a one centimeter length of G75 yarn is(π(9×10⁻⁴/2)²)(400)(2.6 grams per cubic centimeter) (1 centimeter lengthof yarn)=6.62×10⁻⁴ gram mass. For D450 yarn, the Gram Mass is 1.34×10⁻⁴gram mass. The relative drag force per unit mass (“Air Jet TransportDrag Force”) is calculated by dividing the drag force measurement (gramforce) determined by the tensiometer by the Gram Mass for the type ofyarn tested. For example, for a sample of G75 yarn, if the tensiometermeasurement of the drag force is 68.5, then the Air Jet Transport DragForce is equal to 68.5 divided by 6.62×10⁻⁴=103,474 gram force per grammass of yarn.

The Air Jet Transport Drag Force of the yarn used to form a woven fabricfor a laminate according to the present invention, determined accordingto the Air Jet Transport Drag Force Test Method discussed above, can begreater than 100,000 gram force per gram mass of yarn, such as, forexample, from 100,000 to 400,000 gram force per gram mass of yarn, andfrom 120,000 to 300,000 gram force per gram mass of yarn.

The fabric of the present invention can be woven in a style which issuitable for use in a laminate for an electronic support or printedcircuit board, such as are disclosed in “Fabrics Around the World”, atechnical bulletin of Clark-Schwebel, Inc. of Anderson, S.C. (1995),which is specifically incorporated by reference herein. The laminatescan be a unidirectional laminate wherein most of the fibers, yarns orstrands in each layer of fabric are oriented in the same direction.

For example, a nonlimiting fabric style using E225 E-glass fiber yarnsis Style 2116, which has 118 warp yarns and 114 fill (or weft) yarns per5 centimeters (60 warp yarns and 58 fill yarns per inch); uses 7 22 1×0(E225 1/0) warp and fill yarns; has a nominal fabric thickness of 0.094millimeters (about 0.037 inches); and a fabric weight (or basis weight)of 103.8 grams per square meter (about 3.06 ounces per square yard). Anonlimiting example of a fabric style using G75 E-glass fiber yarns isStyle 7628, which has 87 warp yarns and 61 fill yarns per 5 centimeters(44 warp yarns and 31 fill yarns per inch); uses 9 68 1×0 (G75 1/0) warpand fill yarns; has a nominal fabric thickness of 0.173 millimeters(about 0.0068 inches); and a fabric weight of 203.4 grams per squaremeter (about 6.00 ounces per square yard). A nonlimiting example of afabric style using D450 E-glass fiber yarns is Style 1080, which has 118warp yarns and 93 fill yarns per 5 centimeters (60 warp yarns and 47fill yarns per inch); uses 5 11 1×0 (D450 1/0) warp and fill yarns; hasa nominal fabric thickness of 0.053 millimeters (about 0.0021 inches);and a fabric weight of 46.8 grams per square meter (about 1.38 ouncesper square yard). A nonlimiting example of a fabric style using D900E-glass fiber yarns is Style 106, which has 110 warp yarns and 110 fillyarns per 5 centimeters (56 warp yarns and 56 fill yarns per inch); uses5 5.5 1×0 (D900 1/0) warp and fill yarns; has a nominal fabric thicknessof 0.033 millimeters (about 0.013 inches); and a fabric weight of 24.4grams per square meter (about 0.72 ounces per square yard). Anothernonlimiting example of a fabric style using D900 E-glass fiber yarns isStyle 108, which has 118 warp yarns and 93 fill yarns per 5 centimeters(60 warp yarns and 47 fill yarns per inch); uses 5 5.5 1×2 (D900 1/2)warp and fill yarns; has a nominal fabric thickness of 0.061 millimeters(about 0.0024 inches); and a fabric weight of 47.5 grams per squaremeter (about 1.40 ounces per square yard). A nonlimiting example of afabric style using both E225 and D450 E-glass fiber yarns is Style 2113,which has 118 warp yarns and 110 fill yarns per 5 centimeters (60 warpyarns and 56 fill yarns per inch); uses 7 22 1×0 (E225 1/0) warp yarnand 5 11 1×0 (D450 1/0) fill yarn; has a nominal fabric thickness of0.079 millimeters (about 0.0031 inches); and a fabric weight of 78.0grams per square meter (about 2.30 ounces per square yard). Anonlimiting example of a fabric style using both G50 and G75 E-glassfiber yarns is Style 7535 which has 87 warp yarns and 57 fill yarns per5 centimeters (44 warp yarns and 29 fill yarns per inch); uses 9 68 1×0(G75 1/0) warp yarn and 9 99 1×0 (G50 1/0) fill yarn; has a nominalfabric thickness of 0.201 millimeters (about 0.0079 inches); and afabric weight of 232.3 grams per square meter (about 6.85 ounces persquare yard).

These and other useful fabric style specification are given inIPC-EG-140 “Specification for Finished Fabric Woven from ‘E’ Glass forPrinted Boards”, a publication of The Institute for Interconnecting andPackaging Electronic Circuits (June 1997), which is specificallyincorporated by reference herein. Although the aforementioned fabricstyles use twisted yarns, it is contemplated that these or other fabricstyles using zero-twist yarns or rovings in conjunction with or in lieuof twisted yarns can be made in accordance with the present invention.

In an embodiment of the present invention, some or all of the warp yarnin the fabric can have fibers coated with a first resin compatiblesizing composition and some or all of the fill yarn can have fiberscoated with a second resin compatible coating differing from the firstcomposition, i.e., the second composition (1) contains at least onecomponent which is chemically different or differs in form from thecomponents of the first sizing composition; or (2) contains at least onecomponent in an amount which is different from the amount of the samecomponent contained in the first sizing composition.

Referring now to FIG. 7, the fabric 712 can be used to form a compositeor laminate 714 by coating and/or impregnating with a matrix material,such as a polymeric film-forming thermoplastic or thermosetting matrixmaterial 716. The composite or laminate 714 is suitable for use as anelectronic support. As used herein, “electronic support” means astructure that mechanically supports and/or electrically interconnectselements. Examples include, but are not limited to, active electroniccomponents, passive electronic components, printed circuits, integratedcircuits, semiconductor devices and other hardware associated with suchelements including, but not limited to, connectors, sockets, retainingclips and heat sinks.

Certain embodiments of the present invention are directed to areinforced composite comprising at least one partial coated fiber strandcomprising a plurality of fibers discussed in detail above. Reinforcedcomposites made from each of the disclosed fiber strands comprising aplurality of fibers are therefore contemplated by the present invention.For example, one embodiment of the present invention is directed to areinforced composite comprising a matrix material and at least onepartially coated fiber strand comprising a plurality of fibers, thecoating comprising an organic component and lamellar particles having athermal conductivity of at least 1 Watt per meter K at a temperature of300K.

Another embodiment of the present invention is directed to a reinforcedcomposite comprising (a) an at least partially coated fiber strandcomprising a plurality of fibers, the coating comprising at least onelamellar particle, and (b) a matrix material.

Yet another embodiment is directed to a reinforced composite comprising(a) an at least partially coated fiber strand comprising a plurality ofglass fibers, the coating comprising a residue of an aqueous compositioncomprising (i) a plurality of discrete particles formed from materialsselected from organic materials, inorganic polymeric materials,composite materials and mixtures thereof; (ii) at least one lubriciousmaterial different from said plurality of discrete particles; and (iii)at least one film-forming material; and (b) a matrix material.

Still another embodiment of the present invention is directed to areinforced composite comprising at least one fiber strand and a matrixmaterial, wherein the reinforced composite further comprises a residueof an aqueous composition comprising (a) a plurality of discreteparticles formed from materials selected from organic materials,inorganic polymeric materials, composite materials and mixtures thereof;(b) at least one lubricious material different from said plurality ofdiscrete particles; and (c) at least one film-forming material.

Another embodiment of the present invention is directed to a reinforcedcomposite comprising (a) an at least partially coated fiber strandcomprising a plurality of glass fibers, the coating comprising a residueof an aqueous composition comprising greater than 20 weight percent on atotal solids basis of discrete particles which have a Mohs' hardnessvalue which does not exceed a Mohs' hardness value of at least one ofsaid glass fibers; and (b) a matrix material.

Another embodiment is directed to a reinforced composite comprising atleast one fiber strand comprising a plurality of glass fibers and amatrix material, wherein the reinforced composite further comprises aresidue of an aqueous composition comprising greater than 20 weightpercent on a total solids basis of discrete particles which have a Mohs'hardness value which does not exceed a Mohs' hardness value of at leastone of said glass fibers.

An additional embodiment of the present invention is directed to areinforced composite comprising (a) at least one fiber strand comprisinga plurality of glass fibers, the strand coated with a resin compatiblecomposition comprising a plurality of discrete particles formed frommaterials selected from organic materials, inorganic polymericmaterials, composite materials and mixtures thereof, wherein thediscrete particles have an average particle size less than 5micrometers; and (b) a matrix material. In particular, the plurality ofdiscrete particles can be formed from materials selected from non-heatexpandable organic materials, inorganic polymeric materials, non-heatexpandable composite materials, and mixtures of any of the foregoing.

The components of the coatings and resin compatible compositions used inthe foregoing embodiments directed to reinforced composites can beselected from the coating components discussed above, and additionalcomponents can also be selected from those recited above.

Matrix materials useful in the present invention include, but are notlimited to, thermosetting and thermoplastic materials. Nonlimitingexamples of suitable thermosetting materials include thermosettingpolyesters, vinyl esters, epoxides (containing at least one epoxy oroxirane group in the molecule, such as polyglycidyl ethers of polyhydricalcohols or thiols), phenolics, aminoplasts, therm osettingpolyurethanes, derivatives of any of the foregoing, and mixtures of anyof the foregoing. Suitable matrix materials for forming laminates forprinted circuit boards include, but are not limited to, FR-4 epoxyresins, which are polyfunctional epoxy resins such as difunctionalbrominated epoxy resins, polyimides and liquid crystalline polymers, thecompositions of which are well know to those skilled in the art. Iffurther information regarding such compositions is needed, seeElectronic Materials Handbook™, ASM International (1989) at pages534-537, which is specifically incorporated by reference herein.

Nonlimiting examples of suitable polymeric thermoplastic matrixmaterials include polyolefins, polyamides, thermoplastic polyurethanesand thermoplastic polyesters, vinyl polymers, and mixtures of any of theforegoing. Further examples of useful thermoplastic materials include,but are not limited to, polyimides, polyether sulfones, polyphenylsulfones, polyetherketones, polyphenylene oxides, polyphenylenesulfides, polyacetals, polyvinyl chlorides and polycarbonates.

A suitable matrix material formulation consists of EPON 1120-A80 epoxyresin (commercially available from Shell Chemical Company of Houston,Tex.), dicyandiamide, 2-methylimidazole and DOWANOL PM glycol ether(commercially available from The Dow Chemical Co. of Midland, Mich.).

Other components which can be included with the polymeric matrixmaterial and reinforcing material in the composite include, but are notlimited to, colorants or pigments, lubricants or processing aids,ultraviolet light (UV) stabilizers, antioxidants, other fillers andextenders. In one embodiment, inorganic materials can be included withthe polymeric matrix material. These inorganic materials include, butare not limited to, ceramic materials and metallic materials, and can beselected from the inorganic materials described in detail above.

The fabric 712 can be coated and impregnated by dipping the fabric 712in a bath of the polymeric matrix material 716, for example, asdiscussed in R. Tummala (Ed.), Microelectronics Packaging Handbook,(1989) at pages 895-896, which are specifically incorporated byreference herein. More generally, chopped or continuous fiber strandreinforcing material can be dispersed in the matrix material by hand orany suitable automated feed or mixing device which distributes thereinforcing material generally evenly throughout the polymeric matrixmaterial. For example, the reinforcing material can be dispersed in thepolymeric matrix material by dry blending all of the componentsconcurrently or sequentially.

The polymeric matrix material 716 and strand can be formed into acomposite or laminate 714 by a variety of methods which are dependentupon such factors as the type of polymeric matrix material used. Forexample, for a thermosetting matrix material, the composite can beformed by compression or injection molding, pultrusion, filamentwinding, hand lay-up, spray-up or by sheet molding or bulk moldingfollowed by compression or injection molding. Thermosetting polymericmatrix materials can be cured by the inclusion of crosslinkers in thematrix material and/or by the application of heat, for example. Suitablecrosslinkers useful to crosslink the polymeric matrix material arediscussed above. The temperature and curing time for the thermosettingpolymeric matrix material depends upon such factors such as, but notlimited to, the type of polymeric matrix material used, other additivesin the matrix system and thickness of the composite.

For a thermoplastic matrix material, suitable methods for forming thecomposite include, but are not limited to, direct molding or extrusioncompounding followed by injection molding. Methods and apparatus forforming the composite by the above methods are discussed in I. Rubin,Handbook of Plastic Materials and Technology (1990) at pages 955-1062,1179-1215 and 1225-1271, which are specifically incorporated byreference herein.

Additional embodiments of the present invention are directed toreinforced laminates adapted for an electronic support comprising an atleast partially coated fabric comprising at least one fiber stranddiscussed in detail above. Thus, reinforced laminate adapted for anelectronic support made from each of the disclosed fabrics comprising atleast one fiber strand are therefore contemplated by the presentinvention. For example, one embodiment of the present invention isdirected to a reinforced laminate adapted for an electronic supportcomprising a matrix material and an at least one partially coated fabriccomprising at least one fiber strand, the coating comprising an organiccomponent and lamellar particles having a thermal conductivity of atleast 1 Watt per meter K at a temperature of 300K. In a furtherembodiment, the coating is compatible with the matrix material in thereinforced laminate adapted for an electronic support.

An additional embodiment of the present invention is directed to areinforced laminate adapted for an electronic support, the laminatecomprising (a) a matrix material, and at least one non-degreased fabriccomprising at least one fiber strand, at least a portion of the at leastone fabric having a coating which is compatible with the matrix materialin said reinforced laminate adapted for said electronic support. Anotherembodiment of the present invention is directed to a reinforced laminateadapted for an electronic support, the laminate comprising (a) a matrixmaterial, and (b) at least one fabric comprising at least one fiberstrand and having a non-finishing resin compatible coating compositionon at least a portion of a surface of the fabric.

As used herein, a “non-degreased fabric” is a fabric that has notundergone a conventional fiber process removing non-resin compatiblesizing materials from the fabric. As discussed above, heat cleaning andwater-jet washing, in addition to scrubbing are examples of suchconventional fiber processes. As used herein, a “non-finishing” resincompatible coating composition refers to the resin compatible coatingcompositions discussed above that are not used in conventional fiberfinishing processes. For example, a non-finishing resin compatiblecoating composition refers to the primary, secondary and/or tertiarycoating composition discussed above, but does not refer to typicalfinishing sizes made, for example, from a silane coupling agent andwater, and applied to the fiber after degreasing. The present invention,however, does contemplate a coating comprising a resin compatiblecoating according to the present invention with a finishing size appliedto the coating.

Another embodiment of the present invention is directed to a method offorming a laminate for use in an electronic support application, themethod comprising:

(a) obtaining a fabric adapted to reinforce an electronic support formedby weaving at least one fill yarn comprising a plurality of fibers andhaving a first resin compatible coating on at least a portion of the atleast one fill yarn and at least one warp yarn comprising a plurality offibers and having a second resin compatible coating on at least aportion of the at least one warp yarn;

(b) at least partially coating at least a portion of the fabric with amatrix material resin;

(c) at least partially curing the at least partially coated fabric toform a prepreg layer; and

(d) laminating two or more prepreg layers together to form a laminateadapted for use in the electronic support.

The components of the coatings used in the foregoing embodimentsdirected to reinforced laminates can be selected from the coatingcomponents discussed above, and additional components can also beselected from those recited above.

Additional embodiments of the present invention are directed to prepregsfor an electronic support comprising an at least partially coated fabriccomprising at least one fiber strand discussed in detail above. Thus,prepregs for an electronic support made from each of the disclosedfabrics comprising at least one fiber strand are therefore contemplatedby the present invention.

Another embodiment of the present invention is directed a prepreg for anelectronic support, the prepreg comprising (a) a matrix material, and atleast one non-degreased fabric comprising at least one fiber strand, atleast a portion of the at least one fabric having a coating which iscompatible with the matrix material in said prepreg for said electronicsupport. Yet another embodiment of the present invention is directed toa prepreg for an electronic support, the prepreg comprising (a) a matrixmaterial, and (b) at least one fabric comprising at least one fiberstrand and having a non-finishing resin compatible coating compositionon at least a portion of a surface of the fabric.

As above, the components of the coatings used in the foregoingembodiments can be selected from the coating components discussed above,and additional components can also be selected from those recited above.

In a particular embodiment of the invention shown in FIG. 8, compositeor laminate 810 comprises fabric 812 impregnated with a compatiblematrix material 814. The impregnated fabric can then be squeezed betweena set of metering rolls to leave a measured amount of matrix material,and dried to form an electronic support in the form of a semicuredsubstrate or prepreg. An electrically conductive layer 820 can bepositioned along a portion of a side 822 of the prepreg in a manner tobe discussed below in the specification, and the prepreg can be cured toform an electronic support 818 with an electrically conductive layer. Inanother embodiment of the invention, and more typically in theelectronic support industry, two or more prepregs can be combined withone or more electrically conductive layers and laminated together andcured in a manner well known to those skilled in the art, to form amultilayered electronic support. For example, but not limiting thepresent invention, the prepreg stack can be laminated by pressing thestack, e.g. between polished steel plates, at elevated temperatures andpressures for a predetermined length of time to cure the polymericmatrix and form a laminate of a desired thickness. A portion of one ormore of the prepregs can be provided with an electrically conductivelayer either prior to or after lamination and curing such that theresulting electronic support is a laminate having at least oneelectrically conductive layer along a portion of an exposed surface(hereinafter referred to as a “clad laminate”).

Circuits can then be formed from the electrically conductive layer(s) ofthe single layer or multilayered electronic support using techniqueswell known in the art to construct an electronic support in the form ofa printed circuit board or printed wiring board (hereinaftercollectively referred to as “electronic circuit boards”).

Additional embodiments of the present invention are directed toelectronic supports and electronic circuit boards comprising an at leastpartially coated fabric comprising at least one fiber strand discussedin detail above. Thus, electronic supports and electronic circuit boardsmade from each of the disclosed fabrics comprising at least one fiberstrand are therefore contemplated by the present invention.

Another embodiment of the present invention is directed to an electronicsupport comprising (a) at least one non-degreased fabric comprising atleast one fiber strand, at least a portion of the at least onenon-degreased fabric having a coating which is compatible with a matrixmaterial; and (b) at least one matrix material on at least a portion ofthe at least one fabric in the electronic support. An additionalembodiment is directed to an electronic support comprising (a) at leastone fabric comprising at least one fiber strand and having anon-finishing resin compatible coating composition on at least a portionof a surface of the fabric; and (b) at least one matrix material on atleast a portion of the at least one fabric in the electronic support.

Yet another embodiment of the present invention is directed to a methodof forming an electronic support, the method comprising:

(a) obtaining a fabric adapted to reinforce an electronic support formedby weaving at least one fill yarn comprising a plurality of fibers andhaving a first resin compatible coating on at least a portion of the atleast one fill yarn and at least one warp yarn comprising a plurality offibers and having a second resin compatible coating on at least aportion of the at least one warp yarn;

(b) at least partially coating at least a portion of the fabric with amatrix material resin;

(c) at least partially curing the coating into the at least a portion ofthe fabric to form a prepreg layer; and

(d) laminating one or more prepreg layers together with one or moreelectrically conductive layers to form the electronic support.

In a further embodiment, the at least one fabric and the at least onematrix form a first composite layer in the electronic support. Inanother further embodiment, the electronic support further comprises asecond composite layer different from the first composite layer.

An additional embodiment is directed to an electronic circuit boardcomprising (a) an electronic support comprising (i) at least onenon-degreased fabric comprising at least one fiber strand, at least aportion of the at least one non-degreased fabric having a coating whichis compatible with a matrix material, ad (ii) at least one matrixmaterial on at least a portion of the at least one fabric in theelectronic support; and (b) an electronically conductive layer, thesupport and the conductive layer being contained in the electroniccircuit board.

An additional embodiment is directed to an electronic circuit boardcomprising (a) an electronic support comprising (i) at least one fabriccomprising at least one fiber strand and having a non-finishing resincompatible coating composition on at least a portion of a surface of thefabric; and (ii) at least one matrix material on at least a portion ofthe at least one fabric in the electronic support; and (b) anelectronically conductive layer, the support and the conductive layerbeing contained in the electronic circuit board.

In a further embodiment, the electrically conductive layer can bepositioned adjacent to a selected portion of the electronic support. Inanother further embodiment, the at least one fabric and the at least onematrix can form a first composite layer. In another embodiment, theelectronic support can further comprise a second composite layerdifferent from the first composite layer. The electrically conductivelayer can be positioned adjacent to a selected portion of the firstand/or second composite layers electronic support.

Another embodiment of the present invention is directed to a method offorming a printed circuit board, the method comprising:

(a) obtaining an electronic support comprising one or more electricallyconductive layers and at least one fabric adapted to reinforce theelectronic support formed by weaving at least one fill yarn comprising aplurality of fibers and having a first resin compatible coating on atleast a portion of the at least one fill yarn and at least one warp yarncomprising a plurality of glass and having a second resin compatiblecoating on at least a portion of the at least one warp yarn; and

(b) patterning at least one of the one or more electrically conductivelayers of the electronic support to form a printed circuit board.

The components of the coatings used in the foregoing embodimentsdirected to electronic supports and electronic circuit boards can beselected from the coating components discussed above, and additionalcomponents can also be selected from those recited above.

If desired, apertures or holes (also referred to as “vias”) can beformed in the electronic supports, to allow for electricalinterconnection between circuits and/or components on opposing surfacesof the electronic support, by any convenient manner known in the art,including, but not limited to, mechanical drilling and laser drilling.More specifically, referring to FIG. 10, an aperture 1060 extendsthrough at least one layer 1062 of fabric 1012 of an electronic support1054 of the present invention. The fabric 1012 comprises coated fiberstrands comprising a plurality of glass fibers having a layer that iscompatible with a variety of polymeric matrix materials as taughtherein. In forming the aperture 1060, electronic support 1054 ispositioned in registry with an aperture forming apparatus, such as adrill bit 1064 or laser tip. The aperture 1060 is formed through aportion 1066 of the at least one layer 1062 of fabric 1012 by drillingusing the drill 1064 or laser.

In one embodiment, the laminate can have a deviation distance afterdrilling 2000 holes through a stack of 3 laminates at a hole density of62 holes per square centimeter (400 holes per square inch) and a chipload of 0.001 with a 0.46 mm (0.018 inch) diameter tungsten carbidedrill of no greater than 36 micrometers. In an additional embodiment,the laminate has a drill tool % wear after drilling 2000 holes through astack of 3 laminates at a hole density of 62 holes per square centimeter(400 holes per square inch) and a chip load of 0.001 with a 0.46 mm(0.018 inch) diameter tungsten carbide drill of no greater than 32percent.

In further embodiment, a fluid stream comprising an inorganic lubricantcan be dispensed proximate to the aperture forming apparatus such thatthe inorganic lubricant contacts at least a portion of an interfacebetween the aperture forming apparatus and the electronic support. Theinorganic lubricant can be selected from the inorganic lubricantdescribed in detail above.

Another embodiment of the present invention is directed to a method forforming an aperture through a layer of fabric of an electronic systemsupport for an electronic circuit board comprising:

(1) positioning an electronic system support comprising a portion of alayer of fabric comprising a coated fiber strand comprising a resincompatible coating composition on at least a portion of a surface of thefabric, in which an aperture is to be formed in registry with anaperture forming apparatus; and

(2) forming an aperture in the portion of the layer of fabric.

After formation of the apertures, a layer of electrically conductivematerial can be deposited on the walls of the aperture or the aperturecan be filled with an electrically conductive material to facilitate therequired electrical interconnection between one or more electricallyconductive layers (not shown in FIG. 10) on the surface of theelectronic support 1054 and/or heat dissipation. The vias can extendpartially through or entirely through the electronic support and/orprinted circuit board, they can be exposed at one or both surfaces ofthe electronic support and/or printed circuit board or they can becompleted buried or contained within the electronic support and/orcircuit board (“buried via”).

The electrically conductive layer 820 shown in FIG. 8 can be formed byany method well known to those skilled in the art. For example, but notlimiting the present invention, the electrically conductive layer can beformed by laminating a thin sheet or foil of metallic material onto atleast a portion of a side of the semi-cured or cured prepreg orlaminate. As an alternative, the electrically conductive layer can beformed by depositing a layer of metallic material onto at least aportion of a side of the semi-cured or cured prepreg or laminate usingwell known techniques including, but not limited to, electrolyticplating, electroless plating or sputtering. Metallic materials suitablefor use as an electrically conductive layer include, but are not limitedto, copper, silver, aluminum, gold, tin, tin-lead alloys, palladium andcombinations thereof.

In another embodiment of the present invention, the electronic supportcan be in the form of a multilayered electronic circuit boardconstructed by laminating together one or more electronic circuit boards(described above) with one or more clad laminates (described above)and/or one or more prepregs (described above). If desired, additionalelectrically conductive layers can be incorporated into the electronicsupport, for example along a portion of an exposed side of themultilayered electronic circuit board. Furthermore, if required,additional circuits can be formed from the electrically conductivelayers in a manner discussed above. It should be appreciated thatdepending on the relative positions of the layers of the multilayeredelectronic circuit board, the board can have both internal and externalcircuits. Additional apertures can be formed, as discussed earlier,partially through or completely through the board to allow electricalinterconnection between the layers at selected locations. It should beappreciated that the resulting structure can have some apertures thatextend completely through the structure, some apertures that extend onlypartially through the structure, and some apertures that are completelywithin the structure.

The thickness of the laminate forming the electronic support 254 can begreater than 0.051 mm (about 0.002 inches), and can range from 0.13 mm(about 0.005 inches) to 2.5 mm (about 0.1 inches). For an eight plylaminate of 7628 style fabric, the thickness can generally be 1.32 mm(about 0.052 inches). The number of layers of fabric in a laminate canvary based upon the desired thickness of the laminate.

The resin content of the laminate can range from 35 to 80 weightpercent, such as from 40 to 75 weight percent. The amount of fabric inthe laminate can range from 20 to 65 weight percent such as from 25 to60 weight percent.

For a laminate formed from woven E-glass fabric and using an FR-4 epoxyresin matrix material having a minimum glass transition temperature of110° C., the minimum flexural strength in the cross machine or widthdirection (generally perpendicular to the longitudinal axis of thefabric, i.e., in the fill direction) can be greater than 3×10⁷ kg/m²,such as, for example, greater than 3.52×10⁷ kg/m² (about 50 kpsi), andgreater than 4.9×10⁷ kg/m² (about 70 kpsi) according to IPC-4101“Specification for Base Materials for Rigid and Multilayer PrintedBoards” at page 29, a publication of The Institute for Interconnectingand Packaging Electronic Circuits (December 1997). IPC-4101 isspecifically incorporated by reference herein in its entirety. In thelength direction, the desired minimum flexural strength in the lengthdirection (generally parallel to the longitudinal axis of the fabric,i.e., in the warp direction) can be greater than 4×10⁷ kg/m², such asgreater than 4.23×10⁷ kg/m². The flexural strength is measured accordingto ASTM D-790 and IPC-TM-650 Test Methods Manual of the Institute forInterconnecting and Packaging Electronics (December 1994) (which arespecifically incorporated by reference herein) with metal claddingcompletely removed by etching according to section 3.8.2.4 of IPC-4101.Advantages of the electronic supports of the present invention includehigh flexural strength (tensile and compressive strength) and highmodulus, which can lessen deformation of a circuit board including thelaminate.

Electronic supports of the present invention in the form of copper cladFR-4 epoxy laminates can have a coefficient of thermal expansion from50° C. to 288° C. in the z-direction of the laminate (“Z-CTE”), i.e.,across the thickness of the laminate, of less than 5.5 percent, and canrange from 0.01 to 5.0 percent, according to IPC Test Method 2.4.41(which is specifically incorporated by reference herein). Each suchlaminate can contain eight layers of 7628 style fabric, although stylessuch as, but not limited to, 106, 108, 1080, 2113, 2116 or 7535 stylefabrics can alternatively be used. In addition, the laminate canincorporate combinations of these fabric styles. Laminates having lowcoefficients of thermal expansion are generally less susceptible toexpansion and contraction and can minimize board distortion.

The instant invention further contemplates the fabrication ofmultilayered laminates and electronic circuit boards which comprise atleast one composite layer made according to the teachings herein and atleast one composite layer made in a manner different from the compositelayer taught herein, e.g. made using conventional glass fiber compositetechnology. More specifically and as is well known to those skilled inthe art, traditionally the filaments in continuous glass fiber strandsused in weaving fabric can be treated with a starch/oil sizing whichcomprises partially or fully dextrinized starch or amylose, hydrogenatedvegetable oil, a cationic wetting agent, emulsifying agent and water,including, but not limited to, those disclosed in Loewenstein at pages237-244 (3d Ed. 1993), which is specifically incorporated by referenceherein. Warp yarns produced from these strandscan thereafter be treatedwith a solution prior to weaving to protect the strands against abrasionduring the weaving process, e.g. poly(vinyl alcohol) as disclosed inU.S. Pat. No. 4,530,876 at column 3, line 67 through column 4, line 11,which is specifically incorporated by reference herein. This operationis commonly referred to as slashing. The poly(vinyl alcohol) as well asthe starch/oil size are generally not compatible with the polymericmatrix material used by composite manufacturers and the fabric is thuscleaned to remove essentially all organic material from the surface ofthe glass fibers prior to impregnating the woven fabric. This can beaccomplished in a variety ways, for example by scrubbing the fabric or,more commonly, by heat treating the fabric in a manner well known in theart. As a result of the cleaning operation, there is no suitableinterface between the polymeric matrix material used to impregnate thefabric and the cleaned glass fiber surface, so that a coupling agentmust be applied to the glass fiber surface. This operation is sometimereferred to by those skilled in the art as finishing. The couplingagents most commonly used in finishing operations are silanes,including, but not limited to, those disclosed in E. P. Plueddemann,Silane Coupling Agents (1982) at pages 146-147, which is specificallyincorporated by reference herein. Also see Loewenstein at pages 249-256(3d Ed. 1993). After treatment with the silane, the fabric isimpregnated with a compatible polymeric matrix material, squeezedbetween a set of metering rolls and dried to form a semicured prepreg asdiscussed above. It should be appreciated that in the present inventiondepending on the nature of the sizing, the cleaning operation and/or thematrix resin used in the composite, the slashing and/or finishing stepscan be eliminated. One or more prepregs incorporating conventional glassfiber composite technology can then be combined with one or moreprepregs incorporating the instant invention to form an electronicsupport as discussed above, and in particular a multilayered laminate orelectronic circuit board. For more information regarding fabrication ofelectronic circuit boards, see Electronic Materials Handbook™, ASMInternational (1989) at pages 113-115, R. Tummala (Ed.),Microelectronics Packaging Handbook, (1989) at pages 858-861 and895-909, M. W. Jawitz, Printed Circuit Board Handbook (1997) at pages9.1-9.42, and C. F. Coombs, Jr. (Ed.), Printed Circuits Handbook, (3dEd. 1988), pages 6.1-6.7, which are specifically incorporated byreference herein.

The composites and laminates forming the electronic supports of theinstant invention can be used to form packaging used in the electronicsindustry, and more particularly first, second and/or third levelpackaging, such as that disclosed in Tummala at pages 25-43, which isspecifically incorporated by reference herein. In addition, the presentinvention can also be used for other packaging levels.

In one embodiment of the present invention, the flexural strength of anunclad laminate, made in accordance with the present invention from 8layers or plies of prepreg formed from a Style 7628, E-glass fabric andan FR-4 polymeric resin having a T_(g) of 140° C. and tested accordingto IPC-TM-650, No. 2.4.4 (which is specifically incorporated byreference herein), can be greater than 100,000 pounds per square inch(about 690 megaPascals) when tested parallel to the warp direction ofthe fabric, such as greater than 80,000 (about 552 megaPascals) whentested parallel to the fill direction of the fabric.

In another embodiment of the present invention, the short beam shearstrength of an unclad laminate, made in accordance with the presentinvention from 8 layers or plies of prepreg formed from a Style 7628,E-glass fabric and an FR-4 polymeric resin having a T_(g) of 140° C. andtested according to ASTM D 2344-84 (which is specifically incorporatedby reference herein) using a span length to thickness ratio of 5, can begreater than 7400 pounds per square inch (about 51 megaPascals) whentested parallel to the warp direction of the fabric, such as greaterthan 5600 pounds per square inch (about 39 megapascals) when testedparallel to the fill direction of the fabric.

In another embodiment of the present invention, the short beam shearstrength of an unclad laminate, made in accordance with the presentinvention from 8 layers or plies of prepreg formed from a Style 7628,E-glass fabric and an FR-4 polymeric resin having a T_(g) of 140° C. andtested according to ASTM D 2344-84 using a span length to thicknessratio of 5 and after being immersed in boiling water for 24 hours, canbe greater than 5000 pounds per square inch (about 34 megaPascals) whentested parallel to the warp direction of the fabric, such as greaterthan 4200 pounds per square inch (about 30 megaPascals) when testedparallel to the fill direction of the fabric.

The present invention also includes a method for reinforcing a matrixmaterial to form a composite. The method comprises: (1) applying to afiber strand reinforcing material at least one primary, secondary and/ortertiary coating composition discussed in detail above comprisingparticles which provide interstitial spaces between adjacent fibers ofthe strand, (2) drying the coating to form a coating upon thereinforcing material; (3) combining the reinforcing material with thematrix material; and (4) at least partially curing the matrix materialto provide a reinforced composite. Although not limiting the presentinvention, the reinforcing material can be combined with the polymericmatrix material, for example by dispersing it in the matrix material.The coating or coatings can form a substantially uniform coating uponthe reinforcing material upon drying. In one embodiment of the presentinvention, the particles comprise at least 20 weight percent of thesizing composition on a total solids basis. In another embodiment, theparticles can have a minimum average particle dimension of at least 3micrometers, such as at least 5 micrometers. In a further embodiment,the particles have a Mohs' hardness value that can be less than a Mohs'hardness value of any glass fibers that can be contained in the fiberstrand.

The present invention also includes a method for inhibiting adhesionbetween adjacent fibers of a fiber strand, comprising: (1) applying to afiber strand at least one primary, secondary and/or tertiary coatingcomposition discussed in detail above comprising particles which provideinterstitial spaces between adjacent fibers of the strand; (2) dryingthe coating to form a coating upon the fibers of the fiber strand, suchthat adhesion between adjacent fibers of the strand is inhibited. Thecoating or coatings can form a substantially uniform coating upon thereinforcing material upon drying. In one embodiment of the presentinvention, the particles comprise at least 20 weight percent of thesizing composition on a total solids basis. In another embodiment, theparticles can have a minimum average particle dimension of at least 3micrometers, such as at least 5 micrometers. In a spherical particle,for example, the minimum average particle dimension will correspond tothe diameter of the particle. In a rectangularly shaped particle, forexample, the minimum average particle dimension will refer to theaverage length, width or height of the particle. In a furtherembodiment, the particles have a Mohs' hardness value that can be lessthan a Mohs' hardness value of any glass fibers that can be contained inthe fiber strand.

The present invention also includes a method for inhibiting hydrolysisof a matrix material of a fiber-reinforced composite. The methodcomprises: (1) applying to a fiber strand reinforcing material at leastone primary, secondary and/or tertiary coating composition discussed indetail above comprising greater than 20 weight percent on a total solidsbasis of discrete particles; (2) drying the coating to form coating uponthe reinforcing material; (3) combining the reinforcing material withthe matrix material; and (4) at least partially curing the matrixmaterial to provide a reinforced composite. The coating or coatings forma substantially uniform coating upon the reinforcing material upondrying. As discussed above, the reinforcing material can be combinedwith the matrix material, for example, by dispersing the reinforcingmaterial in the matrix material.

In one embodiment of the present invention, the fabric can be woven intoa Style 7628 fabric and has an air permeability of less then 10 cubicfeet per minute such as less than 5 cubic feet per minute, as measuredby ASTM D 737 Standard Test Method for Air Permeability of TextileFabrics. Although not limiting in the present invention, it is believedthat the elongated cross-section and high strand openness of the warpyarns of the present invention (discussed in detail below) reduces theair permeability of the fabrics of the present invention as compared tomore conventional fabrics made using slashed warp yarns.

As previously discussed, in conventional weaving operations forelectronic support applications, the warp yarns can be typically coatedwith a slashing size prior to weaving to help prevent abrasion of thewarp yarns during the weaving process. The slashing size composition istypically applied to the warp yarns by passing the warp yarns through adip pan or bath containing the slashing size and then through one ormore sets of squeeze rolls to remove any excess material. Typicalslashing size compositions can include, for example, film formingmaterials, plasticizers and lubricants. A film-forming material commonlyused in slashing size compositions can be polyvinyl alcohol. Afterslashing, the warp yarns can be dried and wound onto a loom beam. Thenumber and spacing of the warp yarn ends depends on the style of thefabric to be woven. After drying, the slashed warp yarns will typicallyhave a loss on ignition of greater than 2.0 percent due to thecombination of the primary and slashing sizes.

Typically, the slashing sizing, as well as the starch/oil size aregenerally not compatible with the polymeric resin material used bycomposite manufacturers when incorporating the fabric as reinforcementfor an electronic support so that the fabric must be cleaned to removeessentially all organic material from the surface of the glass fibersprior to impregnating the woven fabric. This can be accomplished in avariety ways, for example by scrubbing the fabric or, more commonly, byheat treating the fabric in a manner well known in the art. As a resultof the cleaning operation, there is no suitable interface between thepolymeric matrix material used to impregnate the fabric and the cleanedglass fiber surface, so that a coupling agent must be applied to theglass fiber surface. This operation is sometime referred to by thoseskilled in the art as finishing. Typically, the finishing size providesthe fabric with an LOI less than 0.1%.

After treatment with the finishing size, the fabric can be impregnatedwith a compatible polymeric matrix material, squeezed between a set ofmetering rolls and dried to form a semicured prepreg as discussed above.For more information regarding fabrication of electronic circuit boards,see Electronic Materials Handbook™, ASM International (1989) at pages113-115, R. Tummala (Ed.); Microelectronics Packaging Handbook, (1989)at pages 858-861 and 895-909; M. W. Jawitz, Printed Circuit BoardHandbook (1997) at pages 9.1-9.42; and C. F. Coombs, Jr. (Ed.), PrintedCircuits Handbook, (3d Ed. 1988), pages 6.1-6.7, which are specificallyincorporated by reference herein.

Since the slashing process puts a relatively thick coating on the warpyarns, the yarns become rigid and inflexible as compared to unslashedwarp yarns. The slashing size tends to hold the yarn together in a tightbundle having a generally circular cross-section. Although not meant tobe limiting in the present invention, it is believed that such a yarnstructure (i.e., tight bundles and generally circular cross-sections)can hinder the penetration of polymeric resin materials into the warpyarn bundle during subsequent processing steps, such aspre-impregnation, even after the removal of the slashing size.

Although slashing is not detrimental to the present invention, slashingis not required. Therefore, in one embodiment of the present invention,the warp yarns can not be subjected to a slashing step prior to weavingand can be substantially free of slashing size residue. As used herein,the term “substantially free” means that the warp yarns have less than20 percent by weight, such as less than 5 percent by weight of slashingsize residue. In another embodiment of the present invention, the warpyarns can not be subjected to a slashing step prior to weaving and canbe essentially free of slashing size residue. As used herein, the term“essentially free” means that the warp yarns have less than 0.5 percentby weight, such as, for example, less than 0.1 percent by weight and 0percent by weight of a residue of a slashing size on the surfacesthereof. However, if the warp yarns are subjected to a secondary coatingoperation prior to weaving, the amount of the secondary coating appliedto the surface of the warp yarns prior to weaving can be less than 0.7percent by weight of the sized warp yarn.

In one embodiment of the present invention, the loss on ignition of thewarp yarns can be less than 2.5 percent by weight, such as, for example,less than 1.5 percent by weight and less than 0.8 percent duringweaving. In addition, the fabric of the present invention can have anoverall loss on ignition ranging form 0.1 to 1.6 percent, such as, forexample, from 0.4 to 1.3 percent, and from 0.6 to 1 percent.

In another embodiment of the present invention, the warp yarn can havean elongated cross-section and high strand openness. As used herein, theterm “elongated cross-section” means that the warp yarn has a generallyflat or ovular cross-sectional shape. High strand openness, discussedabove, refers to the characteristic that the individual fibers of theyarn or strand are not tightly held together and open spaces existbetween one or more of the individual fibers facilitating penetration ofa matrix material into the bundle. Slashed warp yarns (as discussedabove) generally have a circular cross-section and low strand opennessand thus do not facilitate such penetration. Although not limiting inthe present invention, it is believed that good resin penetration intothe warp yarn bundles (i.e., good resin wet-out) during lamination canimprove the overall hydrolytic stability of laminates and electronicsupports made in accordance with the present invention, by reducing oreliminating paths of ingress for moisture into the laminates andelectronic supports. This can also have a positive effect in reducingthe tendency of printed circuit boards made from such laminates andelectronic supports to exhibit electrical short failures due to theformation of conductive anodic filaments when exposed, under bias, tohumid conditions.

The degree of strand openness can be measured by an F-index test. In theF-index test, the yarn to be measured is passed over a series ofvertically aligned rollers and is positioned adjacent to a horizontallydisposed sensing device comprising a light emitting surface and anopposing light sensing surface, such that a vertical axis of the yarn isin generally parallel alignment with the light emitting and lightsensing surfaces. The sensing device is mounted at a vertical heightthat positions it about half-way between the vertically aligned rollersand the horizontal distance between the yarn and the sensing device iscontrolled by moving the rollers toward or away from the sensing device.As the yarn passes over the rollers (typically at about 30 meters perminute), depending on the openness of the strand, one or more portionsof the yarn can eclipse a portion of the light emanating from theemitting surface thereby triggering a response in the light sensingsurface. The number of eclipses are then tabulated for a given length ofyarn (typically about 10 meters) and the resulting ratio (i.e., numberof eclipses per unit length) is considered to be a measure of strandopenness.

It is believed that the tight warp yarn structure of fabric woven fromconventional, slashed glass fiber yarns as well as the low openness ofsuch yarns as discussed above, results in these conventional fabricshaving an air permeability that is higher than the air permeability ofcertain fabrics of the present invention, which can include an elongatedwarp yarn cross-section and higher warp yarn openness. In one embodimentof the present invention, the fabric has an air permeability, asmeasured by ASTM D 737 Standard Test Method, of no greater than 10standard cubic feet per minute per square foot (about 0.05 standardcubic meters per minute per square meter), such as, for example, nogreater than 5 cubic feet per minute per square foot (1.52 standardcubic meters per minute per square meter), and no greater than 3 cubicfeet per minute per square foot (0.91 standard cubic meters per minuteper square meter). In another embodiment of the invention, the fabriccan be woven into a 7628 style fabric and has an air permeability, asmeasured by ASTM D 737 Standard Test Method. of no greater than 10standard cubic feet per minute per square foot, such as, for example, nogreater than 5 cubic feet per minute per square foot, and no greaterthan 3 cubic feet per minute per square foot.

Although not meant to be bound or in any way limited by any particulartheory, it is postulated that warp yarns having elongated or flatcross-sections can also lend to improved drilling performance inlaminates made from fabrics incorporating the warp yarns. Moreparticularly, since the cross over points between the warp and fillyarns in fabrics having warp yarns with elongated cross-sections willhave a lower profile than conventional fabrics incorporating warp yarnshaving circular cross-sections, a drill bit drilling through the fabricwill contact fewer glass fibers during drilling and thereby be subjectedto less abrasive wear.

As previously discussed, in one embodiment of the present invention,both the warp yarns and the fill yarns can have a resin compatibleprimary coating composition applied thereto during forming. The resincompatible primary coating composition applied to the warp yarn can bethe same as the resin compatible primary coating composition applied tothe fill yarn or it can be different from the resin compatible primarycoating composition applied to the fill yarn. As used herein, the phrase“different from the resin compatible primary coating composition appliedto the fill yarn” in reference to the resin compatible primary coatingcomposition applied to the warp yarn means that at least one componentof the primary coating composition applied to the warp yarn is presentin an amount different from that component in the primary coatingcomposition applied to the fill yarn or that at least one componentpresent in the primary coating composition applied to the warp yarn isnot present in the primary coating composition applied to the fill yarnor that at least one component present in the primary coatingcomposition applied to the fill yarn is not present in the primarycoating composition applied to the warp yarn.

In still another embodiment of the present invention, the glass fibersof the yarns of the fabric can be E-glass fibers having a density ofless than 2.60 grams per cubic centimeter. In still another embodiment,the E-glass fiber yarns, when woven into a Style 7628 fabric, produce afabric having a tensile strength parallel to the warp direction that canbe greater than the strength (in the warp direction) of conventionallyheat-cleaned and finished fabrics of the same style. In one embodimentof the present invention, the resin compatible primary coatingcomposition can be substantially free of “tacky” film-forming materials,i.e., the primary coating composition can comprise less than 10 percentby weight on a total solids basis, such as less than 5 percent by weighton a total solids basis.

In one embodiment, the resin compatible primary coating composition canbe essentially free of “tacky” film-forming materials, i.e., the primarycoating composition can comprise less than 1 percent by weight on atotal solids basis, such as, for example, less than 0.5 percent byweight on a total solids basis, and less than 0.1 percent by weight on atotal solids basis of tacky film-forming materials. Tacky film-formingmaterials can be detrimental to the weavability of yarns to which theyare applied, such as by reducing the air-jet transportability of fillyarns and causing warp yarns to stick to each other. A specific,nonlimiting example of a tacky film-forming material can be awater-soluble epoxy resin film-forming material.

An alternative method of forming a fabric for use in an electronicsupport application according to the present invention will now bediscussed generally. The method comprises: (1) obtaining at least onefill yarn comprising a plurality of glass fibers and having a firstresin compatible coating applied to at least a portion thereof; (2)obtaining at least one warp yarn comprising a plurality of glass fibersand having a second resin compatible coating applied to at least aportion thereof; and (3) weaving the at least one fill yarn and the atleast one warp yarn having a loss on ignition of less than 2.5 percentby weight to form a fabric adapted to reinforce an electronic support.

A method of forming a laminate adapted for use in an electronic supportwill now be discussed generally. The method comprises obtaining a fabricformed by weaving at least one fill yarn comprising a plurality of glassfibers and having a first resin compatible coating applied to at least aportion thereof and at least one warp yarn comprising a plurality ofglass fibers and having a second resin compatible coating applied to atleast a portion thereof wherein the warp yarn had a loss on ignition ofless than 2.5 percent by weight during weaving. In one embodiment of thepresent invention, the fabric can be essentially free of slashing sizeresidue.

As previously discussed, in typical fabric forming operations, theconventional sizing compositions applied to the glass fibers and/oryarns (i.e., primary sizing compositions and slashing size compositions)are not resin compatible and therefore must be removed from the fabricprior to impregnating the fabric with polymeric resin materials. Asdescribed above, this is most commonly accomplished by heat cleaning thefabric after weaving. However, heat cleaning degrades the strength ofthe glass fibers (and therefore the yarns and fabrics formed therefrom)and causes the glass to densify. The resin compatible coatings of thepresent invention, which are applied to the warp and/or fill yarns priorto weaving, do not require removal prior to impregnation and therebyeliminate the need for heat-cleaning. Therefore, in an embodiment of thepresent invention, the fabric can be free from thermal treatment andthermal degradation prior to impregnation.

Additionally, in conventional fabric forming processes, after removal ofthe sizing compositions by heat cleaning, a finishing size must beapplied to the fabric prior to impregnation to improve the compatibilitybetween the fabric and the polymeric resin. By applying a resincompatible coating to the warp and/or fill yarns prior to weaving in thepresent invention, the need for fabric finishing can also be eliminated.Therefore, in another embodiment of the present invention, the fabriccan be substantially free of residue from a secondary coating and/or afinishing size, i.e., less than 15 percent by weight, such as less than10 percent by weight of residue from a secondary coating and/or afinishing size. In another embodiment of the present invention, thefabric can be essentially free of residue from a secondary coatingand/or a finishing size. As used herein, the term “essentially free”means that the fabric has less than 1 percent by weight, such as lessthan 0.5 percent by weight of residue from a secondary coating and/or afinishing size.

The present invention provides non-heat cleaned glass fiber fabricscomprising resin compatible coatings that offer higher tensile strengthsthan corresponding fabrics that have been heat cleaned and silanefinished. These fabrics can be used in a wide variety of applications,such as reinforcements for composites such as printed circuit boards.

In one nonlimiting embodiment, the invention provides a non-heat cleanedfabric comprising a plurality of fiber strands in a warp direction and afill direction, each fiber strand comprising a plurality of E-glassfiber, and having a resin compatible coating composition on at least aportion of a surface of at least one fiber strand, wherein the fabrichas a tensile strength of at least 267 Newtons when measured in the warpdirection or fill direction. Although not required, the fabric also hasa tensile strength of at least 1.5 times that of a corresponding fabricthat is heat cleaned by heating the corresponding fabric to atemperature of at least 380° C. for at least 60 hours and silanefinished when measured in the warp direction or fill direction.

The present invention also provides a non-heat cleaned fabric comprisinga plurality of fiber strands in a warp and a fill direction, each of thefiber strands comprising a plurality of E-glass fibers, and having aresin compatible coating composition on at least a surface of the atleast one fiber strand, wherein the fabric has a tensile strength of atleast 1.5 times that of a corresponding fabric that is heat cleaned byheating the corresponding fabric to a temperature of at least 380° C.for at least 60 hours when measured in the warp direction or the filldirection.

The present invention further provides a laminate comprising: a) atleast one matrix material; and b) at least one non-heat cleaned fabriccomprising a plurality of fiber strands in a warp direction and a filldirection, each of the fiber strands comprising a plurality of E-glassfibers, and having a resin compatible coating composition on at least asurface of at least one fiber strand, wherein the fabric has a tensilestrength of at least 267 Newtons when measured in the warp direction orthe fill direction.

The present invention also provides a laminate comprising: a) at leastone matrix material; and b) at least one non-heat cleaned fabriccomprising a plurality of fiber strands in a warp direction and a filldirection, each of the fiber strands comprising a plurality of E-glassfibers, and having a resin compatible coating composition on at least asurface of at least one fiber strand, wherein the fabric has a tensilestrength of at least 1.5 times that of a corresponding fabric that isheat cleaned by heating the corresponding fabric to a temperature of atleast 380° C. for at least 60 hours and silane finished when measured inthe warp direction or the fill direction.

The present invention further provides electronic supports comprisingthe laminates discussed above.

Nonlimiting examples of resin compatible coatings of the type disclosedin the present invention are shown in Table D.

TABLE D WEIGHT PERCENT OF COMPONENT ON TOTAL SOLIDS BASIS Examples A E FH COMPONENT (77B) B C D (18L) (18H) G (78) PVP K-30⁹⁷ 13.7 13.4 13.513.4 15.3 14.2 STEPANTEX 653⁹⁸ 27.9 27.3 13.6 12.6 A-187⁹⁹ 1.7 1.6 1.91.9 2.3 2.3 1.9 1.7 A-l74¹⁰⁰ 3.4 3.3 3.8 3.8 4.8 4.8 3.8 3.5 EMERY6717¹⁰¹ 2.3 2.2 1.9 1.9 2.5 2.4 MACOL OP-10¹⁰² 1.5 1.5 1.7 1.6TMAZ-81¹⁰³ 3.0 3.0 3.4 3.1 MAZU DF-136¹⁰⁴ 0.2 0.2 0.3 0.2 ROPAQUEOP-96¹⁰⁵ 39.3 38.6 43.9 40.7 RELEASECOAT-CONC 25¹⁰⁶ 4.2 6.3 6.4 3.8 4.5POLARTHERM PT 160¹⁰⁷ 2.7 2.6 2.6 5.9 2.8 SAG 10¹⁰⁸ 0.2 0.2 RD-847A¹⁰⁹23.2 23.0 DESMOPHEN 2000¹¹⁰ 31.2 31.0 44.4 44.1 PLURONIC F-108¹¹¹ 8.58.4 10.9 ALKAMULS EL-719¹¹² 3.4 2.5 ICONOL NP-6¹¹³ 3.4 4.2 3.6 POLYOXWSR 301¹¹⁴ 0.6 0.6 DYNAKOLL Si 100¹¹⁵ 29.1 28.9 SERMUL EN 668¹¹⁶ 2.9SYNPERONIC F-108¹¹⁷ 10.9 EUREDUR 140¹¹⁸ 4.9 VERSAMID 140¹¹⁹ 4.8 FLEXOLEPO¹²⁰ 13.6 12.6 ⁹⁷PVP K-30 polyvinyl pyrrolidone which is commerciallyavailable from ISP Chemicals of Wayne, New Jersey. ⁹⁸STEPANTEX 653 whichis commercially available from Stepan Company of Maywood, New Jersey.⁹⁹A-187 gamma-glycidoxypropyltrimethoxysilane which is commerciallyavailable from CK Witco Corporation of Tarrytown, New York. ¹⁰⁰A-174gamma-methacryloxypropyltrimethoxysilane which is commercially availablefrom CK Witco Corporation of Tarrytown, New York. ¹⁰¹EMERY ® 6717partially amidated polyethylene imine which is commercially availablefrom Cognis Corporation of Cincinnati, Ohio. ¹⁰²MACOL OP-10 ethoxylatedalkylphenol; this material is similar to MACOL OP-10 SP except thatOP-10 SP receives a post treament to remove the catalyst; MACOL OP-10 isno longer commercially available. ¹⁰³TMAZ-81 ethylene oxide derivativeof a sorbitol ester which is commercially available from BASF Corp. ofParsippany, New Jersey. ¹⁰⁴MAZU DF-136 antifoaming agent which iscommercially available from BASF Corp. of Parsippany, New Jersey.¹⁰⁵ROPAQUE ® OP-96, 0.55 micron particle dispersion which iscommercially available from Rohm and Haas Company of Philadelphia,Pennsylvania. ¹⁰⁶ORPAC BORON NITRIDE RELEASECOAT-CONC 25 boron nitridedispersion which is commercially available from ZYP Coatings, Inc. ofOak Ridge, Tennessee. ¹⁰⁷POLARTHERM ® PT 160 boron nitride powder whichis commercially available from Advanced Ceramics Corporation ofLakewood, Ohio. ¹⁰⁸SAG 10 antiforming material, which is commerciallyavailable from CK Witco Corporation of Greenwich, Connecticut.¹⁰⁹RD-847A polyester resin which is commercially available from BordenChemicals of Columbus, Ohio. ¹¹⁰DESMOPHEN 2000 polyethylene adipate diolwhich is commercially available from Bayer Corp. of Pittsburgh,Pennsylvania. ¹¹¹PLURONIC ™ F-108 polyoxypropylene-polyoxyethylenecopolymer which is commercially available from BASF Corporation ofParsippany, New Jersey. ¹¹²ALKAMULS EL-719 polyoxyethylated vegetableoil which is commercially available from Rhone-Poulenc. ¹¹³ICONOL NP-6alkoxylated nonyl phenol which is commercially available from BASFCorporation of Parsippany, New Jersey. ¹¹⁴POLYOX WSR 301 poly(ethyleneoxide) which is commercially available from Union Carbide Corp. ofDanbury, Connecticut. ¹¹⁵DYNAKOLL Si 100 rosin which is commerciallyavailable from Eka Chemicals AB, Sweden. ¹¹⁶SERMUL EN 668 ethoxylatednonylphenol which is commercially available from CON BEA, Benelux.¹¹⁷SYNPERONIC F-108 polyoxypropylene-polyoxyethylene copolymer; it isthe European counterpart to PLURONIC F-108. ¹¹⁸EUREDUR 140 is apolyamide resin, which is commercially available from Ciba Geigy,Belgium. ¹¹⁹VERSAMID 140 polyamide resin which is commercially availablefrom Cognis Corp. of Cincinnati, Ohio. ¹²⁰FLEXOL EPO epoxidized soybeanoil commercially available from Union Carbide of Danbury, Connecticut.

Additional nonlimiting examples of glass fiber yarns and fabricscomprising a resin compatible coating, and electronic supportscomprising these glass fiber yarns and fabrics are disclosed in U.S.application Ser. No. 09/620,526 entitled “Impregnating Glass FiberStrands and Products Including the Same” and filed Nov. 3, 2000, theexamples of which are hereby incorporated by reference.

The present invention will now be illustrated by the following specific,nonlimiting example.

EXAMPLE

As discussed earlier, the fabrics of the present invention incorporate aresin compatible coating on the fabric and/or fibers and do not requirefurther processing prior to coating the fabric with a resin matrixmaterial, and in particular, do not require heat cleaning to remove thefabric coating and subsequently coating the heat cleaned fabric with asilane finishing treatment. Furthermore, it is believed that exposure ofthe fabric to the elevated temperatures used in a heat cleaningoperation, typically at least 380° C. (716° F.) for at least 60-80 hoursfor glass fiber fabrics, will reduce the tensile strength of the glassfiber strands and the fabric. Table 1 shows the tensile strength ofE-glass fiber 7628 style fabric subjected to different coatings andprocessing. The tensile strength of the fabrics was tested in both thefill and warp directions. Fabric A incorporated fill yarn coated withthe resin compatible coating identified as Sample A in Table D. The warpyarn was coated with the resin compatible coating identified as Sample Fin Table D. Fabric A was not heat cleaned. Fabric B was a heat cleanedbut not silane finished fabric provided by J. P. Stevens of Slater, S.C.This fabric with a silane finish is commercially available from J. P.Stevens as a heat cleaned and silane finished electrical grade 7628style fabric for epoxy resin. However, for the purposes of this test,the fabric without the silane finish was tested. Fabric C was a heatcleaned and silane finished electrical grade 7628 style fabric for epoxyresin commercially available from Bedford Weaving of Lynchburg, Va.Fabric D was a fabric woven with warp and fill yarns coated with PPG 695sizing, which is a starch-oil sizing commercially available from PPGIndustries, Inc. of Pittsburgh, Pa. Fabric D was not heat cleaned sothat the polyvinyl alcohol containing slashing size applied to the warpyarn for weaving was still on the fabric during testing. Fabric E wasthe same as Fabric D except after weaving, the fabric was heated for 15minutes at 343° C. (650° F.). A silane finish was not applied to FabricE after heating.

The tensile strength of the fabrics was determined in accordance withthe testing procedures in ASTM D 5035-95. However and in accordance toSection 11.7 of the ASTM D 5035 test procedures, in order to preventslippage between the jaw face of the clamp used to hold the ends of thefabric during testing, glass fiber prepregs were glued to the jaw facearea of the fabric by epoxy resin adhesive.

TABLE 1 Fabric Breaking Load Style Fabric Treatment Fill/Warp (N) (lbf)Fabric A resin compatible coating Fill 1579 355 7628 not heat cleanedWarp 2046 460 Fabric B starch-oil coating Fill 258 58 7628 heat cleanedWarp 436 98 not silane finished Fabric C starch-oil coating Fill 347 787628 heat cleaned Warp 627 141 silane finished Fabric D starch-oilcoating Fill 1735 390 7628 includes PVA slashing Warp 2028 456 not heatcleaned Fabric E starch-oil coating Fill 1308 294 7628 modified heatcleaning Warp 1557 350 not silane finished

As can be seen in Table 1, the glass fiber fabrics that were notsubjected to heat treatment, i.e. Fabrics A and D, had the highesttensile strength in both the warp and fill directions. In comparingnon-heat cleaned resin compatible Fabric A with heat cleaned and silanefinished Fabric C, both of which fabrics would be incorporated with aresin matrix material as reinforcement, e.g. in electronic supports, itis apparent that Fabric A has a significantly higher tensile strength.In particular, the tensile strength of Fabric A is at least 3 times thatof Fabric C when tested in the warp direction and at least 4 times thatof Fabric C when tested in the fill direction. In addition, in comparingnon-heat cleaned resin compatible Fabric A with non-silane finishedFabric B, the tensile strength of Fabric A is at least 4 times that ofFabric B when tested in the warp direction and at least 6 times that ofFabric B when tested in the fill direction. It is also observed whencomparing heat cleaned Fabric B with heat cleaned and silane finishedFabric C that the silane finish tends to increase the tensile strengthof the heat cleaned fabric; however the resulting tensile strength isstill significantly less than the tensile strength of non-heat cleanedresin compatible Fabric A. In addition when comparing Fabric D withFabric E, it is apparent that even a small amount of heating will reducethe tensile strength of the fabric.

Table 2 shows the results of additional tensile strength testingperformed on E-glass fiber 2116 and 1080 style fabrics in a manner asdiscussed earlier. Fabrics F and H incorporated fill yarn coated withthe resin compatible coating identified as Sample A in Table D and warpyarn coated with the resin compatible coating Sample F shown in Table D.Fabric G was a heat cleaned and silane finished electrical grade 2116style fabric for epoxy resin commercially available from J. P. Stevens.Fabric I was a heat cleaned and silane finished electrical grade 1080style fabric for epoxy resin commercially available from J. P. Stevens.

TABLE 2 Fabric Breaking Load Style Fabric Treatment Fill/Warp (N) (lbf)Fabric F resin compatible coating Fill 792 178 2116 not heat cleanedWarp 672 151 Fabric G starch-oil coating Fill 182 41 2116 heat cleanedWarp 222 50 silane finished Fabric H resin compatible coating Fill 41493 1080 not heat cleaned Warp 418 94 Fabric I starch-oil coating Fill125 28 1080 heat cleaned Warp 254 57 silane finished

In comparing non-heat cleaned resin compatible Fabrics F and H with heatcleaned and silane finished Fabrics H and 1, all of which fabrics wouldbe incorporated with a resin matrix material as reinforcement, e.g. inelectronic supports, it is apparent that the non-heat cleaned resincompatible fabrics have a significantly higher tensile strength. Inparticular, with respect to the 2116 style fabrics, the tensile strengthof Fabric F is at least 3 times that of Fabric G when tested in the warpdirection and at least 4 times that of Fabric G when tested in the filldirection. With respect to the 1080 style fabrics, the tensile strengthof Fabric H is at least 1.60 times that of Fabric I when tested in thewarp direction and at least 3 times that of Fabric I when tested in thefill direction

Based on the above, in one nonlimiting embodiment of the presentinvention, the tensile strength of non-heat cleaned glass fiber fabriccoated with a resin compatible coating, such as but not limited to aresin compatible coating of the type disclosed herein, is at least 1.5times that of a corresponding glass fiber fabric that was heat cleanedby heating the fabric to at least 380° C. (716° F.) for at least 60hours and silane finished when tested in the warp direction or in thefill direction. As used herein, “corresponding fabric” means a fabricthat is woven in the same fabric style and from the same type of fibermaterial. In another nonlimiting embodiment of the present invention,the tensile strength of non-heat cleaned glass fiber fabric coated witha resin compatible coating, e.g. as disclosed, herein is at least 3times that of a corresponding fabric that was heat cleaned by heatingthe fabric to at least 380° C. (716° F.) for at least 60 hours andsilane finished when tested in the warp direction or in the filldirection or in both the warp and fill directions. In other nonlimitingembodiments of the present invention, the tensile strength of thenon-heat cleaned glass fiber fabric coated with a resin compatiblecoating, e.g. as disclosed herein, is at least 2 times, or at least 3times, that of a corresponding glass fiber fabric that was heat cleanedby heating the fabric to at least 380° C. (716° F.) for at least 60hours but not silane finished when tested in the warp direction or inthe fill direction or in both the warp and fill directions. In othernonlimiting embodiments of the present invention, the tensile strengthof a non-heat cleaned glass fiber fabric coated with a resin compatiblecoating, e.g. as disclosed herein, is at least 267 Newtons (60 lbf), orat least 445 Newtons (100 lbf), or at least 667 Newtons (150 lbf), or atleast 1334 Newtons (300 lbf, when tested in the warp direction or in thefill direction.

In several other nonlimiting embodiments of the present invention, thetensile strength of a non-heat cleaned 7628 style glass fiber fabriccoated with a resin compatible coating, e.g. as disclosed herein, is atleast 1.5 times, or at least 2 times, or at least 3 times, that of acorresponding 7628 style glass fiber fabric that was heat cleaned byheating the fabric to at least 380° C. (716° F.) for at least 60 hoursand silane finished when tested in the warp direction or in the filldirection. In other nonlimiting embodiment of the present invention, thetensile strength of a non-heat cleaned 7628 style glass fiber fabriccoated with a resin compatible coating, e.g. as disclosed herein, is atleast 4 times that of a corresponding 7628 style glass fiber fabric thatwas heat cleaned by heating the fabric to at least 380° C. (716° F.) forat least 60 hours and silane finished when tested in the fill direction.In other nonlimiting embodiments of the present invention, the tensilestrength of a non-heat cleaned 7628 style glass fiber fabric coated witha resin compatible coating, e.g. as disclosed herein, is at least 667Newtons (150 lbf), or at least 890 Newtons (200 lbf), or at least 1334Newtons (300 lbf) when tested in the warp direction or in the filldirection.

In several other nonlimiting embodiments of the present invention, thetensile strength of a non-heat cleaned 2116 style glass fiber fabriccoated with a resin compatible coating, e.g. as disclosed herein, is atleast 1.5 times, or at least 2 times or at least 3 times, that of acorresponding 2116 style glass fiber fabric that was heat cleaned byheating the fabric to at least 380° C. (716° F.) for at least 60 hoursand silane finished when tested in the warp direction or in the filldirection. In other nonlimiting embodiment of the present invention, thetensile strength of a non-heat cleaned 2116 style glass fiber fabriccoated with a resin compatible coating, e.g. as disclosed herein, is atleast 4 times that of a corresponding 2116 style glass fiber fabric thatwas heat cleaned by heating the fabric to at least 380° C. (716° F.) forat least 60 hours and silane finished when tested in the fill direction.In other nonlimiting embodiments of the present invention, the tensilestrength of a non-heat cleaned 2116 style glass fiber fabric coated witha resin compatible coating, e.g. as disclosed herein, is at least 267Newtons (60 lbf), or at least 445 Newtons (100 lbf, or at least 667Newtons (150 lbf), when tested in the warp direction or in the filldirection.

In several other nonlimiting embodiments of the present invention, thetensile strength of a non-heat cleaned 1080 style glass fiber fabriccoated with a resin compatible coating, e.g. as disclosed herein, is atleast 1.2 times, or at least 1.5 times, or at least 1.6 times, that of acorresponding 1080 style glass fiber fabric that was heat cleaned byheating the fabric to at least 380° C. (716° F.) for at least 60 hoursand silane finished when tested in the warp direction. In othernonlimiting embodiments of the present invention, the tensile strengthof a non-heat cleaned 1080 style glass fiber fabric coated with a resincompatible coating, e.g. as disclosed herein, is at least 1.5 times, orat least 2 times, or at least 3 times, that of a corresponding 1080style glass fiber fabric that was heat cleaned by heating the fabric toat least 380° C. (716° F.) for at least 60 hours and silane finishedwhen tested in the fill direction. In other nonlimiting embodiments ofthe present invention, the tensile strength of a non-heat cleaned 1080style glass fiber fabric coated with a resin compatible coating, e.g. asdisclosed herein, is at least 267 Newtons (60 lbf, or is at least 334Newtons (75 lbf, or at least 400 Newtons (90 lbf), when tested in thewarp direction or in the fill direction.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications that are within the spirit and scopeof the invention, as defined by the appended claims.

What is claimed is:
 1. A non-heat cleaned fabric comprising a pluralityof fiber strands in a warp direction and a fill direction, each fiberstrand comprising a plurality of E-glass fiber, and having a resincompatible coating composition on at least a portion of a surface of atleast one fiber strand, wherein the fabric has a tensile strength of atleast 267 Newtons when measured in the warp direction or fill direction.2. A fabric according to claim 1, wherein the fabric has a tensilestrength of 445 Newtons.
 3. A fabric according to claim 2, wherein thefabric has a tensile strength of 667 Newtons.
 4. A fabric according toclaim 3, wherein the fabric has a tensile strength of 1334 Newtons.
 5. Afabric according to claim 1, wherein the fabric has a tensile strengthof at least 1.5 times that of a corresponding fabric that is heatcleaned by heating the corresponding fabric to a temperature of at least380° C. for at least 60 hours and silane finished when measured in thewarp direction or fill direction.
 6. A fabric according to claim 5,wherein the fabric has a tensile strength of at least 2 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours andsilane finished when measured in the warp direction or fill direction.7. A fabric according to claim 6, wherein the fabric has a tensilestrength of at least 3 times that of a corresponding fabric that is heatcleaned by heating the corresponding fabric to a temperature of at least380° C. for at least 60 hours and silane finished when measured in thewarp direction or fill direction.
 8. A fabric according to claim 1,wherein the fabric is selected from 7628, 2116 and 1080 style fabrics.9. A fabric according to claim 8, wherein the fabric is a 7628 stylefabric and the tensile strength is at least 667 Newtons.
 10. A fabricaccording to claim 9, wherein the fabric has a tensile strength of atleast 890 Newtons.
 11. A fabric according to claim 10, wherein thefabric has a tensile strength of at least 1334 Newtons.
 12. A fabricaccording to claim 8, wherein the fabric is a 2116 style fabric and hasa tensile strength of at least 445 Newtons.
 13. A fabric according toclaim 12, wherein the fabric has a tensile strength of at least 667Newtons.
 14. A fabric according to claim 8, wherein the fabric is a 1080style fabric and has a tensile strength of at least 334 Newtons.
 15. Afabric according to claim 14, wherein the fabric has a tensile strengthof at least 400 Newtons.
 16. A fabric according to claim 8, wherein thefabric has a tensile strength of at least 1.5 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours andsilane finished when measured in the warp direction or fill direction.17. A fabric according to claim 16, wherein the fabric has a tensilestrength of at least 2 times that of a corresponding fabric that is heatcleaned by heating the corresponding fabric to a temperature of at least380° C. for at least 60 hours and silane finished when measured in thewarp direction or fill direction.
 18. A fabric according to claim 17,wherein the fabric has a tensile strength of at least 3 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours andsilane finished when measured in the warp direction or fill direction.19. A fabric according to claim 8, wherein the fabric is a 7628 stylefabric and has a tensile strength of at least 4 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours andsilane finished when measured in the fill direction.
 20. A fabricaccording to claim 8, wherein the fabric is a 2116 style fabric and hasa tensile strength of at least 4 times that of a corresponding fabricthat is heat cleaned by heating the corresponding fabric to atemperature of at least 380° C. for at least 60 hours and silanefinished when measured in the fill direction.
 21. A fabric according toclaim 8, wherein the fabric is a 1080 style fabric and has a tensilestrength of at least 1.2 times that of a corresponding fabric that isheat cleaned by heating the corresponding fabric to a temperature of atleast 380° C. for at least 60 hours and silane finished when measured inthe warp direction.
 22. A fabric according to claim 21, wherein thefabric has a tensile strength of at least 1.6 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours andsilane finished when measured in the warp direction.
 23. A fabricaccording to claim 1, wherein the resin compatible coating compositioncomprises a plurality of particles.
 24. A fabric according to claim 23,wherein the plurality of particles are formed from materials selectedfrom polymeric inorganic materials, non-polymeric inorganic materials,polymeric organic materials, non-polymeric organic materials, compositematerials, and mixtures of any of the foregoing.
 25. A fabric accordingto claim 24, wherein the polymeric inorganic materials are selected frompolyphosphazenes, polysilanes, polysiloxane, polygeremanes, polymericsulfur, polymeric selenium, silicones, and mixtures of any of theforegoing.
 26. A fabric according to claim 24, wherein the non-polymericinorganic materials are selected from graphite, metals, oxides,carbides, nitrides, borides, sulfides, silicates, carbonates, sulfates,hydroxides, and mixtures of any of the foregoing.
 27. A fabric accordingto claim 24, wherein the polymeric organic materials are selected from(a) thermosetting materials selected from thermosetting polyesters,vinyl esters, epoxy materials, phenolics, aminoplasts, thermosettingpolyurethanes, carbamate functional polymers, and mixtures of any of theforegoing, (b) thermoplastic materials selected from thermoplasticpolyesters, polycarbonates, polyolefins, acrylic polymers, polyamides,thermoplastic polyurethanes, vinyl polymers, and mixtures of any of theforegoing, and (c) mixtures of the thermosetting materials andthermoplastic materials.
 28. A fabric according to claim 23, wherein theplurality of particles have a thermal conductivity of at least 1 Wattper meter K at a temperature of 300 K.
 29. A fabric according to claim23, wherein the plurality of particles have a Mohs' hardness value whichdoes not exceed the Mohs' hardness value of at least one fiber of theplurality of E-glass fibers.
 30. A fabric according to claim 23, whereinthe plurality of particles have a Mohs' hardness value ranging from 0.5to
 6. 31. A fabric according to claim 23, wherein the plurality ofparticles have an average particle size sufficient to allow strand wetout.
 32. A fabric according to claim 31, wherein the plurality ofparticles have an average particle size, measured according to laserscattering techniques, ranging from 0.1 to 5 microns.
 33. A fabricaccording to claim 23, wherein the resin compatible coating compositionfurther comprises at least one lubricious material different from theplurality of particles.
 34. A fabric according to claim 23, wherein theresin compatible coating composition comprises at least one film-formingmaterial.
 35. A fabric according to claim 1, wherein the resincompatible coating composition comprises a resin reactive diluentcomprising a lubricant comprising one or more functional groups capableof reacting with an epoxy resin system and selected from the groupconsisting of amine groups, alcohol groups, anhydride groups, acidgroups and epoxy groups.
 36. A fabric according to claim 1, wherein theresin compatible coating composition is a residue of at least oneaqueous coating composition.
 37. A non-heat cleaned fabric comprising aplurality of fiber strands in a warp and a fill direction, each of thefiber strands comprising a plurality of E-glass fibers, and having aresin compatible coating composition on at least a surface of the atleast one fiber strand, wherein the fabric has a tensile strength of atleast 1.5 times that of a corresponding fabric that is heat cleaned byheating the corresponding fabric to a temperature of at least 380° C.for at least 60 hours when measured in the warp direction or the filldirection.
 38. A fabric according to claim 37, wherein the fabric has atensile strength of at least 2 times that of a corresponding fabric thatis heat cleaned by heating the corresponding fabric to a temperature ofat least 380° C. for at least 60 hours when measured in the warpdirection or the fill direction.
 39. A fabric according to claim 38,wherein the fabric has a tensile strength of at least 3 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours whenmeasured in the warp direction or the fill direction.
 40. A laminatecomprising: a) at least one matrix material; and b) at least onenon-heat cleaned fabric comprising a plurality of fiber strands in awarp direction and a fill direction, each of the fiber strandscomprising a plurality of E-glass fibers, and having a resin compatiblecoating composition on at least a surface of at least one fiber strand,wherein the fabric has a tensile strength of at least 267 Newtons whenmeasured in the warp direction or the fill direction.
 41. A laminateaccording to claim 40 wherein the fabric has a tensile strength of atleast 445 Newtons.
 42. A laminate according to claim 41, wherein thefabric has a tensile strength of at least 667 Newtons.
 43. A laminateaccording to claim 40, wherein the fabric has a tensile strength of atleast 1.5 times that of a corresponding fabric that is heat cleaned byheating the corresponding fabric to a temperature of at least 380° C.for at least 60 hours and silane finished when measured in the warpdirection or the fill direction.
 44. A laminate according to claim 43,wherein the fabric has a tensile strength of at least 2 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours andsilane finished when measured in the warp direction or the filldirection.
 45. A laminate comprising: a) at least one matrix material;and b) at least one non-heat cleaned fabric comprising a plurality offiber strands in a warp direction and a fill direction, each of thefiber strands comprising a plurality of E-glass fibers, and having aresin compatible coating composition on at least a surface of at leastone fiber strand, wherein the fabric has a tensile strength of at least1.5 times that of a corresponding fabric that is heat cleaned by heatingthe corresponding fabric to a temperature of at least 380° C. for atleast 60 hours and silane finished when measured in the warp directionor the fill direction.
 46. A laminate according to claim 45, wherein thefabric has a tensile strength of at least 2 times that of acorresponding fabric that is heat cleaned by heating the correspondingfabric to a temperature of at least 380° C. for at least 60 hours andsilane finished when measured in the warp direction or the filldirection.
 47. An electronic support comprising the laminate accordingto claim 40.